Leveling 29g stand...

[Euclid]

I've got an assortment of "shims" under the stand's feet right now but I'm not very happy with how sturdy it is.
I've seen feet attached to screws on some stands before, does anybody know what these are called? Where could I get some? Would they be sturdy enough for my 29g?
Turns out the subflooring where I put my tank is ridiculously not level...

Thanks!

[fjr_wertheimber]

Self-leveling feet. Both Home Depot and Lowes carry them, look in the furniture hardware section. They've got them rated for different weight capacities.