One of the common questions we get about our Riser Bases are if the feet should be a little loose. The simple answer is yes. The steel sheets that our products are cut from are made within a range of tolerances - some are a little thinner while others can be a little thicker. It's impossible to perfectly match the gap in the feet with the thickness of the steel on the riser. Because of this, we size the gap in the feet to match the thickest sheets we receive from the manufacturer to make sure that they will always slide on.
In practice, this has no effect on how the unit performs. Once the feet are slid onto the Riser Base and it's placed inside of the Pyro Cage for use, the sides of the cage "lock" the Riser Base in place so that it can't move. If you plan to move your Riser Base often, one option is to use a hammer to hit the top of the feet so that they "bite" into the Riser Base.