"You can save a lot of money from buying a separete lid than buying a combo most times.
I love these lids! I have them on all my reptile tanks and they are great. They can take a beating and stand up to a lot of heat. The sizes from what I've noticed are a little loose, so don't use them for snakes or rats.
The 10gallon fits a 10 or 15, the 20 fits and 20 HIGH, and the 29gallon fits a 20 LONG. A little confusing, sorry.
Overall these are great lids and are for a great price. Can't beat it!!!"