I'm a firm believe in no over crowding rodents. That small litter pan is 6" shorter than a ten gallon tank. There is no way that I would run 1.4 in there. You have the potential for five adults and 40+ babies in there. I wouldn't do it. The only way I would run them THAT HIGH in THAT BIN is if I were just pulling pinks. Then it doesn't really matter.

For about a dollar more you can get the Petmate value line litter pans, which are substantially bigger and perfect for running 1.4 mice in.