GS Products offer 60mm steel cup hooks. These wood screw M hooks are made with BZP steel and are very corrosive resistant.
M8 x 25mm Cup Square Bolt Galvanised - F H Brundle
Boat Hooks, Dock Hooks & Telescoping Hook Poles
60mm A2 MARINE GRADE STAINLESS STEEL WOOD THREAD HEAVY DUTY SCREW CUP HOOKS 60MM
Hex Full Nut M8 Galvanised - F H Brundle
Hardware & Ironmongery Product Guide by Centurion Europe - Issuu
Timco Screws Fixings Warehouse
Zinc Plated Steel Screw Hooks 18g x 100mm
ForgeFix Machine Screw Pozi Compatible Pan Head ZP M6 x 50mm Forge
SH605081# Setscrew UNF 5/16 X 1 Inch
Zinc-plated Large Cup hook (L)60mm, Pack of 10
Zinc-plated Medium Cup hook (L)40mm, Pack of 25
Screw Hooks
Hooks - Reliable Fasteners
Zinc Plated (BZP) Hex Head Screws - M16 x L 70mm, 8.8 Grade