Flange Vented Cap For M18 Screws, ID 17.2mm x Flange Diameter 30mm, 50mm Long, Silicone (Red), Pack of 25, HLCS18-B
SGD $95.00
Vented caps have a ribbed internal structure to make attachment easy onto axles. Also has an exhaust port that can be utilized with simple drilling. Externally, the step design makes it easy to remove.