Simfix

M6 X 40 Cup Square Bolt 10 Pack DIN 603 A2 Stainless Steel

SKU 603A206040PK10-SIM
1000+ in stockReady to dispatch
£5.70
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M6 x 40mm coach bolt in A2 stainless steel to DIN 603. The domed round head and square neck lock against the timber face, preventing rotation during tightening - ideal for outdoor timber structures, fencing, gates, and garden furniture. A2 (304 grade) gives good corrosion resistance for indoor and non-coastal outdoor use. Free next-day UK delivery on orders over £50.
£5.70

M6 x 40mm coach bolt in A2 stainless steel to DIN 603. The domed round head and square neck lock against the timber face, preventing rotation during tightening - ideal for outdoor timber structures, fencing, gates, and garden furniture. A2 (304 grade) gives good corrosion resistance for indoor and non-coastal outdoor use. Free next-day UK delivery on orders over £50.
  • M6 x 40mm coach bolt A2 stainless DIN 603 stainless steel
  • DIN 603 coach bolt M6 x 40mm A2 stainless steel, side profile
  • Domed head detail - M6 x 40mm A2 stainless coach bolt DIN 603
  • Cup Square Bolt in a real-life outdoor application. The square neck helps resist turning in timber connections.
  • Simfix product label - 603A206040PK10-SIM
  • Simfix product label - 603A206040PK50-SIM
M6 x 40mm coach bolt A2 stainless DIN 603 stainless steel
DIN 603 coach bolt M6 x 40mm A2 stainless steel, side profile
Domed head detail - M6 x 40mm A2 stainless coach bolt DIN 603
Cup Square Bolt in a real-life outdoor application. The square neck helps resist turning in timber connections.
Simfix product label - 603A206040PK10-SIM
Simfix product label - 603A206040PK50-SIM
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M6 x 40mm coach bolt A2 stainless DIN 603 stainless steel DIN 603 coach bolt M6 x 40mm A2 stainless steel, side profile Domed head detail - M6 x 40mm A2 stainless coach bolt DIN 603 Cup Square Bolt in a real-life outdoor application. The square neck helps resist turning in timber connections. Simfix product label - 603A206040PK10-SIM Simfix product label - 603A206040PK50-SIM
M6 x 40mm coach bolt A2 stainless DIN 603 stainless steel DIN 603 coach bolt M6 x 40mm A2 stainless steel, side profile Domed head detail - M6 x 40mm A2 stainless coach bolt DIN 603 Cup Square Bolt in a real-life outdoor application. The square neck helps resist turning in timber connections. Simfix product label - 603A206040PK10-SIM Simfix product label - 603A206040PK50-SIM

This M6 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. 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 in outdoor structures, fencing, and play equipment.

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-day UK delivery on orders over £50 and 30-day no-quibble returns.

*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 styleCup square bolt with square neck
StandardDIN 603
MaterialA2 stainless steel (304)
Property classA2-70
Thread sizeM6
Thread pitch1.0 mm (coarse)
Length40 mm
Head typeCup square (carriage)
Drive typeNo head drive (nut tightened with spanner)
Surface finishPlain (no plating)
HS commodity code7318159585
Recommended useOutdoor

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 4pm 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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