M12/M16/M20/M24 Stainless Steel A2/A4/304/316 Easy Tighten Railway Square Head Bolt - China Square Head Bolt, Easy Tighten Bolt | Made-in-China.com
4-Point Sockets for Square-Head Bolts | Blacksmiths Depot
Vogueing Tool Hook Wrench Square Head Spanner Adjustable C Spanner for Turning Nut or Bolt (32-76MM) : Amazon.co.uk: DIY & Tools
Model Engineering and engineering tools online from RDG Tools Ltd Home Page (Engineering Tools) Tel 01422 885069 /884605
What tool can I use to unscrew a screw with a square shape hole? I want something like an Allen wrench because it's blocked by the sink so there's very little space. -