Any aspen will be fine, but if you want to buy in bulk for cheap I recommend using just plain softwood shavings. Any farm supply store in your area should have it. I use it for 3 rat tubs and 14 snake tubs and as a general rule one bag, costing about $7.00, lasts me for 3 - 4 months. I agree with KMG about double posting. If another post isn't getting a response just post in it to bump it back to the top.