Rugged computer tower stands with wheels?

I have a server tower with these dimensions:

Height: 17.7 inches
Width: 9.1 inches
Depth: 20.5 inches
Weight: About 40lbs

I've tried those plastic made computer stands with wheels, but over time they end up breaking. They aren't used harshly, just to roll them in and out to service the machine.

I'm looking for a product recommendation. I've seen a couple of metal ones online, but I'm conceed the tower might slip out of it when its wheels out for service.