It can protect the bearings against dust and water. big cap on the outside that will be with a O ring seal inside to protect the bearing on same side.
Per set includes a pair of nut cap and a threaded axle.
TO buy the part on our eBay shop
The price of our eBay is higher than here because it charges us more than 13% fee.
The price just includes PayPal fee, buyer pays VAT and customs tax.