Flange Vented Cap For M10 Screws, ID 9.2mm x Flange Diameter 20mm, 25mm Long, Silicone (Tea), Pack of 10, HLCS10-2-P
SGD $21.80
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.