It is pine..and yes before anyone goes on about it *LOL*...i've heard the big debate on its bad for rodents....my mice have been on it for many years with no ill effects...they like to dig in it and they pick it up and take it into their nesting boxes. Personally i think if a rodent is predisposed/or more likely to get respiratory disease , then no matter what you put them on they'll get it

I've tried lucerne pellets...too darned expensive when you have 5 tanks/cages of mice/rats changed every 3 days..

Shredded white paper (i can get tonnes of that) is horrible stuff & newspaper is worse...does nothing for smell and it terrible to clean up once wet, stains your mice and looks bad in my opinion

I've looked into getting paper pellets (kitty litter)...but am having trouble getting my hands on bulk quantites...as soon as i can i'll more than likely change to that, just so i don't have this query every time *LOL*