These are lids that fit 12x12x12/ 12x12x18or 12x12x24″ Exo Terra terrariums, but please ensure yours are the newer Exo Terra with swivel clamps (2010 onward), not the spring-loaded push-in lids. Cheaper than you’ll find anywhere! Limited quantity. If you have old model Exos, you’ll need to use a sharp razor blade or pliers to cut the tabs off of the top of your tank.