8mm Hex Allen Key Insex Lobed Hand Wheel Knob for boat outboard fuel tank cap with indicator etc
Simple Lobed Hand Wheel to make it easy to tighten/loosen the ventilation screw in outboard fuel tank cap with indicator
STL / STEP / Fusion360 .f3d
example for Sweden:
https://www.biltema.se/bat/batmotor/bransletillbehor/bransletankar/tanklock-2429-l-2000034785
or Google for instance "Can-sb Vented Cap With Level Indicator"