Simfix
M16 X 40 Cup Square Bolt 10 Pack DIN 603 A2 Stainless Steel
- RRP
- £22.33
This M16 x 40mm coach bolt (cup square head bolt) is manufactured to DIN 603 in A2 stainless steel (304 grade). DIN 603 specifies a domed round head with a small square neck directly below the head. Property class A2-70 indicates a minimum tensile strength of 700 MPa - stronger than standard A2-50 and suited to structural fixings where higher clamping force is needed. When drawn into timber, the square neck embeds into the timber face and locks the bolt against rotation, so only the nut needs a spanner during tightening. The smooth domed head on the visible face reduces snag risk and gives a neat appearance.
Typical applications
- Timber-to-timber and timber-to-steel connections with a flush round head
- Garden gates, fencing panels, and agricultural timber structures
- Play equipment, outdoor furniture, and landscape installations
- Pergolas, decking subframes, and structural outdoor joinery
Available in packs of 10 to 50, with free next working day delivery on UK orders over £50 and 30-day returns. For coastal, marine, or chloride-rich environments, Simfix A4 (316 grade) equivalents are available.
- RRP
- £22.33
This M16 x 40mm coach bolt (cup square head bolt) is manufactured to DIN 603 in A2 stainless steel (304 grade). DIN 603 specifies a domed round head with a small square neck directly below the head. Property class A2-70 indicates a minimum tensile strength of 700 MPa - stronger than standard A2-50 and suited to structural fixings where higher clamping force is needed. When drawn into timber, the square neck embeds into the timber face and locks the bolt against rotation, so only the nut needs a spanner during tightening. The smooth domed head on the visible face reduces snag risk and gives a neat appearance.
Typical applications
- Timber-to-timber and timber-to-steel connections with a flush round head
- Garden gates, fencing panels, and agricultural timber structures
- Play equipment, outdoor furniture, and landscape installations
- Pergolas, decking subframes, and structural outdoor joinery
Available in packs of 10 to 50, with free next working day delivery on UK orders over £50 and 30-day returns. For coastal, marine, or chloride-rich environments, Simfix A4 (316 grade) equivalents are available.
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Complete the fixing
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M16 X 40 Cup Square Bolt DIN 603 A2 Stainless Steel
Total for selected
This M16 x 40mm coach bolt (cup square head bolt) is manufactured to DIN 603 in A2 stainless steel (304 grade). DIN 603 specifies a domed round head with a small square neck directly below the head. Property class A2-70 indicates a minimum tensile strength of 700 MPa - stronger than standard A2-50 and suited to structural fixings where higher clamping force is needed. When drawn into timber, the square neck embeds into the timber face and locks the bolt against rotation, so only the nut needs a spanner during tightening. The smooth domed head on the visible face reduces snag risk and gives a neat appearance.
Typical applications
- Timber-to-timber and timber-to-steel connections with a flush round head
- Garden gates, fencing panels, and agricultural timber structures
- Play equipment, outdoor furniture, and landscape installations
- Pergolas, decking subframes, and structural outdoor joinery
Available in packs of 10 to 50, with free next working day delivery on UK orders over £50 and 30-day returns. For coastal, marine, or chloride-rich environments, Simfix A4 (316 grade) equivalents are available.
*Photos, diagrams and other images are for illustration only and may not show the exact item supplied. Simfix reserves the right to alter or replace any photo, diagram or image at any time at its sole discretion.
**Orders that cannot be split will be rounded up to the next full pack or box quantity.
Simfix reserves the right to change quantities, stock levels and prices at any time. We accept no liability for the accuracy of dimensional data, DIN/ISO references, technical data, customs tariff codes or EAN barcodes.
| Fastener style | Cup square bolt |
|---|---|
| Standard | DIN 603 |
| Material | A2 stainless steel (304) |
| Property class | A2-70 |
| Thread size | M16 |
| Length | 40 mm |
| Head type | Cup Head |
| Drive type | Square |
| Surface finish | Plain (no plating) |
| Recommended use | Outdoor |
RoHS and REACH compliant.
How do I choose between A2 and A4 stainless steel?
A2 (304) stainless steel suits most indoor, outdoor and workshop jobs. Choose A4 (316) marine grade for coastal, marine, poolside or other chloride-rich environments.
How do I make sure I order the right size?
Check the size in the product title and the standard, material and dimensions in the Product Specification tab. In M8 x 30, M8 is the thread diameter and 30 is the length in millimetres. See our size guide if you need more help.
When will my order arrive?
Orders placed before 3:30pm Monday-Friday are typically dispatched the same working day and every order is tracked. Next-day delivery is free over £50, or £5.50 below that threshold. Full options are shown at checkout.
What if I order the wrong item?
Email contact@simfix.com within 30 days of delivery with your order number. We will help arrange a refund or replacement. See our refunds information for the full process.
Is checkout secure?
Yes. Checkout is protected by SSL encryption and payments are processed through Shopify's secure checkout and supported payment providers. Simfix does not store your full card details.
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