It's called
Dry Den. It's actually a horse stall bedding, so it absorbs quite a bit! It's been lasting me around 10 days, though I could probably go longer, because there's no urine smell, even while stirring it up during cleaning. The poos tend to stay on top, so if you're someone that can't stand that... I get it for about $5 a bag (with sales tax)--and a cage change for a 2x4 with a 1x2 loft takes a little over 1 bag. I'm going to be switching to fleece, though--I just realized I have access to old beat up motel bedspreads for free!