Filling with a solution that is too hot can warp the plastic & damage the mechanisms. Containers are not "water tight", so pouring too hot can also cause leaking (until the formulation solidifies). Compatibility testing is always recommended. Set includes natural round twist-up tube w/screw-on cap. 2 oz (57g) capacity Polypropylene. #5 Recyclable BPA Free (Product is not manufactured with BPA, BPS, DEHP, DBP, BBP, DINP, DIDP, DNOP, PFOA, PFOS, PVC, HIPS Mercury or Lead) HEIGHT W/OUT CAP: 4" HEIGHT W/CAP: 5" DIAMETER: 1.5" LABEL AREA AROUND CONTAINER: 5" LABEL AREA HEIGHT: 3" COMPATIBLE LABEL SIZES: 4x2, 2.75x2.75, 2x2, 1.67" Circle, 2.5" Circle (1x2.625 or .5x1.75 will also work, but are very small compared to size of container) Please note that container has a slight taper, so labels larger than those recommended will need to be tested.