4mm allen (hexagon) key

• Manufacturers: Various
• Product ID: Various

Any 4mm allen key is fine. IN practice you're probably better getting a set as you also need a 5mm allen key.

Supplier Links

https://www.amazon.co.uk/Draper-33603-4-0mm-Metric-Hexagon/dp/B00XYU3RFS/ref=sr_1_3

Indicative Pricing With Allowance for P&P

You're probably better getting a set but if you do just want them individually you can do. I've seen them on eBay individually for as little as £1

£1

Substitutions

None