Inserts - Expansion - Press In - 303 Stainless Steel

7 Products in this selection

A selection of 303 Stainless Steel Press In Expansion Inserts. Use for cored or drilled holes in plastics. Designed to replace molded in inserts and threads in plastic casings. Also known as threaded inserts.

  • Used to create a reusable threaded hole in a material by expanding once it is in place.
  • Installed by being pressed into a pre-drilled hole, and a subsequent tightening of a screw or bolt causes it to expand and grip the material's interior, providing a strong, stable connection.
  • Common types are for wood, plastic, and masonry, with different designs tailored to the material's properties.
  • Material : 303 Stainless Steel
  • Easiest inserts to install - simply push into a pre-moulded hole.
  • Used with plastics or other materials. Material must be strong enough to withstand the expansion of the insert.
  • The insertion of the screw locks the external knurls into the wall of the hole.
  • Provides excellent thread durability but where maximum strength is required other inserts shown in this catalogue should be preferred.
Small Parts & Bearings

Additional resources:
Assortment Kits

A more comprehensive listing may be found on the MBA Minibearings main store at Inserts - Expansion - Press In - 303 Stainless Steel.
Internal Thread Rec. Hole Diameter Length (L) Recommended Hole Diameter (A) Knurled OD (B) Indicative
Image
Internal Thread
2-56 UNC (2.18mm)
Rec. Hole Diameter
3.17
mm
+ 0.000 / - 0.254
(Equiv. 0.125 in.)
Length (L)
3.96
mm
+/- 0.25
(Equiv. 0.156 in.)
Knurled OD (B)
3.18
mm
Expansion Inserts - 2-56 UNC - 2.18mm - 3.17x3.96 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80   
Part Number: IN-EP-022C-039-S3 (Each) Expansion Inserts - 2-56 UNC - 2.18mm - 3.17x3.96 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
20 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$4.86 AUD
$5.84 AUD $4.86 AUD
Each
Internal Thread Rec. Hole Diameter Length (L) Recommended Hole Diameter (A) Indicative
Image
Internal Thread
2-56 UNC (2.18mm)
Rec. Hole Diameter
3.17
mm
+ 0.000 / - 0.254
(Equiv. 0.125 in.)
Length (L)
3.96
mm
+/- 0.25
(Equiv. 0.156 in.)
Expansion Inserts - 2-56 UNC - 2.18mm - 3.17x3.96 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80    Knurled OD (B): 3.18 mm   
Part Number: IN-EP-022C-039-S3 (Each) Expansion Inserts - 2-56 UNC - 2.18mm - 3.17x3.96 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
20 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$4.86 AUD
$5.84 AUD $4.86 AUD
Each
View the product page first if you are unsure.
Internal Thread
4-40 UNC (2.85mm)
Rec. Hole Diameter
3.96
mm
+ 0.000 / - 0.254
(Equiv. 0.156 in.)
Length (L)
4.78
mm
+/- 0.25
(Equiv. 0.188 in.)
Knurled OD (B)
3.97
mm
Expansion Inserts - 4-40 UNC - 2.85mm - 3.96x4.78 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80   
Part Number: IN-EP-029C-048-S3 (Each) Expansion Inserts - 4-40 UNC - 2.85mm - 3.96x4.78 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
20 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$4.95 AUD
$4.95 AUD
Each
Internal Thread
4-40 UNC (2.85mm)
Rec. Hole Diameter
3.96
mm
+ 0.000 / - 0.254
(Equiv. 0.156 in.)
Length (L)
4.78
mm
+/- 0.25
(Equiv. 0.188 in.)
Expansion Inserts - 4-40 UNC - 2.85mm - 3.96x4.78 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80    Knurled OD (B): 3.97 mm   
Part Number: IN-EP-029C-048-S3 (Each) Expansion Inserts - 4-40 UNC - 2.85mm - 3.96x4.78 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
20 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$4.95 AUD
$4.95 AUD
Each
View the product page first if you are unsure.
Internal Thread
6-32 UNC (3.5mm)
Rec. Hole Diameter
4.75
mm
+ 0.000 / - 0.254
(Equiv. 0.187 in.)
Length (L)
6.35
mm
+/- 0.25
(Equiv. 0.25 in.)
Knurled OD (B)
4.77
mm
Expansion Inserts - 6-32 UNC - 3.5mm - 4.75x6.35 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80   
Part Number: IN-EP-035C-064-S3 (Each) Expansion Inserts - 6-32 UNC - 3.5mm - 4.75x6.35 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
30 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$3.59 AUD
$3.59 AUD
Each
Internal Thread
6-32 UNC (3.5mm)
Rec. Hole Diameter
4.75
mm
+ 0.000 / - 0.254
(Equiv. 0.187 in.)
Length (L)
6.35
mm
+/- 0.25
(Equiv. 0.25 in.)
Expansion Inserts - 6-32 UNC - 3.5mm - 4.75x6.35 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80    Knurled OD (B): 4.77 mm   
Part Number: IN-EP-035C-064-S3 (Each) Expansion Inserts - 6-32 UNC - 3.5mm - 4.75x6.35 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
30 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$3.59 AUD
$3.59 AUD
Each
View the product page first if you are unsure.
Internal Thread
8-32 UNC (4.17mm)
Rec. Hole Diameter
5.53
mm
+ 0.000 / - 0.254
(Equiv. 0.218 in.)
Length (L)
7.95
mm
+/- 0.25
(Equiv. 0.313 in.)
Knurled OD (B)
5.54
mm
Expansion Inserts - 8-32 UNC - 4.17mm - 5.53x7.95 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80   
Part Number: IN-EP-042C-079-S3 (Each) Expansion Inserts - 8-32 UNC - 4.17mm - 5.53x7.95 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
10 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$9.86 AUD
$9.86 AUD
Each
Internal Thread
8-32 UNC (4.17mm)
Rec. Hole Diameter
5.53
mm
+ 0.000 / - 0.254
(Equiv. 0.218 in.)
Length (L)
7.95
mm
+/- 0.25
(Equiv. 0.313 in.)
Expansion Inserts - 8-32 UNC - 4.17mm - 5.53x7.95 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80    Knurled OD (B): 5.54 mm   
Part Number: IN-EP-042C-079-S3 (Each) Expansion Inserts - 8-32 UNC - 4.17mm - 5.53x7.95 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
10 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$9.86 AUD
$9.86 AUD
Each
View the product page first if you are unsure.
Internal Thread
10-32 UNF (4.76mm)
Rec. Hole Diameter
6.34
mm
+ 0.000 / - 0.254
(Equiv. 0.25 in.)
Length (L)
9.53
mm
+/- 0.25
(Equiv. 0.375 in.)
Knurled OD (B)
6.35
mm
Expansion Inserts - 10-32 UNF - 4.76mm - 6.34x9.53 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80   
Part Number: IN-EP-048F-095-S3 (Each) Expansion Inserts - 10-32 UNF - 4.76mm - 6.34x9.53 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
10 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$4.68 AUD
$5.62 AUD $4.68 AUD
Each
Internal Thread
10-32 UNF (4.76mm)
Rec. Hole Diameter
6.34
mm
+ 0.000 / - 0.254
(Equiv. 0.25 in.)
Length (L)
9.53
mm
+/- 0.25
(Equiv. 0.375 in.)
Expansion Inserts - 10-32 UNF - 4.76mm - 6.34x9.53 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80    Knurled OD (B): 6.35 mm   
Part Number: IN-EP-048F-095-S3 (Each) Expansion Inserts - 10-32 UNF - 4.76mm - 6.34x9.53 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
10 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$4.68 AUD
$5.62 AUD $4.68 AUD
Each
View the product page first if you are unsure.
Internal Thread
1/4-20 UNC (6.35mm)
Rec. Hole Diameter
7.93
mm
+ 0.000 / - 0.254
(Equiv. 0.312 in.)
Length (L)
12.70
mm
+/- 0.25
(Equiv. 0.5 in.)
Knurled OD (B)
7.94
mm
Expansion Inserts - 1/4-20 UNC - 6.35mm - 7.93x12.7 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80   
Part Number: IN-EP-064C-127-S3 (Each) Expansion Inserts - 1/4-20 UNC - 6.35mm - 7.93x12.7 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
6 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$7.14 AUD
$8.56 AUD $7.14 AUD
Each
Internal Thread
1/4-20 UNC (6.35mm)
Rec. Hole Diameter
7.93
mm
+ 0.000 / - 0.254
(Equiv. 0.312 in.)
Length (L)
12.70
mm
+/- 0.25
(Equiv. 0.5 in.)
Expansion Inserts - 1/4-20 UNC - 6.35mm - 7.93x12.7 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80    Knurled OD (B): 7.94 mm   
Part Number: IN-EP-064C-127-S3 (Each) Expansion Inserts - 1/4-20 UNC - 6.35mm - 7.93x12.7 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
6 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$7.14 AUD
$8.56 AUD $7.14 AUD
Each
View the product page first if you are unsure.
Internal Thread
5/16-18 UNC (7.94mm)
Rec. Hole Diameter
9.52
mm
+ 0.000 / - 0.254
(Equiv. 0.375 in.)
Length (L)
14.30
mm
+/- 0.25
(Equiv. 0.563 in.)
Knurled OD (B)
9.53
mm
Expansion Inserts - 5/16-18 UNC - 7.94mm - 9.52x14.3 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80   
Part Number: IN-EP-079C-143-S3 (Each) Expansion Inserts - 5/16-18 UNC - 7.94mm - 9.52x14.3 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
6 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$7.05 AUD
$8.45 AUD $7.05 AUD
Each
Internal Thread
5/16-18 UNC (7.94mm)
Rec. Hole Diameter
9.52
mm
+ 0.000 / - 0.254
(Equiv. 0.375 in.)
Length (L)
14.30
mm
+/- 0.25
(Equiv. 0.563 in.)
Expansion Inserts - 5/16-18 UNC - 7.94mm - 9.52x14.3 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
Material: Stainless Steel 303/304 (Similar to A2, 18-8) HRB80    Knurled OD (B): 9.53 mm   
Part Number: IN-EP-079C-143-S3 (Each) Expansion Inserts - 5/16-18 UNC - 7.94mm - 9.52x14.3 mm Press In - Stainless Steel 303/304 Similar to A2, 18-8 HRB80 Insert
6 Available Now | Further orders can be expected around Tue, Jul 21, 2026
$7.05 AUD
$8.45 AUD $7.05 AUD
Each
View the product page first if you are unsure.