Snap Caps are easy to apply to the vial and useful for HPLC samples that are not highly volatile. Septa: Types - Cross Slit, Low Bleed, Non-Slit, Other, Partial Slit, Pre-Slit, PTFE only, PTFE/Silicone Rubber/PTFE, Star Slit, Tan Color, White Sil/PTFE/Sil or Y ...