These square vials work great for slings and come pre-ventilated at the top. (it's fairly minimal ventilation, so be conservative when adding moisture) They can be used for arboreal slings by filling about 1/3 with substrate or for terrestrial/fossorial slings by filling about 1/2 with substrate. The lid has a little thumb tab to help open the larger side more easily but pro tip: you can pop open the little side almost as easily in cases where the spider is inconveniently located, OR maybe you just want to have a smaller opening because your 8 legged race car is a butthead.
They come in 2 sizes.
Short = 2.3x2.3x4.2 inches
Tall = 2.3x2.3x5.2"
Make it a Kit! Selecting this option will add the following to the vial. 1 baggie with an appropriate level of substrate, 1 baggie with a small amount of sphagnum moss, 1 modified XS oyster mushroom ledge, and 1x small or extra small Corner tree hide. Currently colors will be Shane's choice, but if you message immediately after ordering, he will probably consider requests for standard colors. ;)