I had to change the wheels on the sliding gate of my house and I wanted a wheel that could be easily removed for maintenance or replacement, was made of stainless steel and had sealed bearings. This 3" wheel block ticks all my boxes and didn't break the bank! This H slot wheel is high quality at a good price. Wheels and bracket are made of stainless steel for durability. The wheel is held in place by a stainless steel axle with locking rings on each side. Sealed bearings can be easily removed by hand for easy maintenance. They are sold as an assembly and shipped from "WUHAN, CHINA". If you don't mind the monthly wait, this is a great deal.