Grainger offers a wide selection of thumb caps and bottle closures made of a variety of materials in assorted shapes and sizes. Find LDPE thumb caps that can resist most acids, alcohols, bases and esters to help tightly and safely seal glass test tubes. Choose the type of liner materials you need in screw-on phenolic caps to seal and reseal glass specimen bottles and other containers. Check out a huge variety of cap and closure types that can fit a wide range of neck sizes. Shop Grainger for thumb caps and bottle closures today!