In a stack of 2 it works great, I don’t use it as much as I thought I might. If you have them stacked 3 high the lower one will stick to the point of not being able to slide it in initially. I suspect if you were able to slide in even the thinnest of spacers between the bottom 2 that would probably solve the problem but I bought them for loaded up racks. I also suspect they would work on a 3 stack of empty racks but once you put animals in it might stick. This is on the VE-6’s, I havent tried it on the 70’s.