Flange Vented Cap For M10 Screws, ID 9.2mm x Flange Diameter 22mm, 50mm Long, Silicone (Tea), Pack of 100, HLCS10-B
SGD $247.50
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.