Made of polypropylene. This shoulderless vial features a full width opening of 23mm for ease of access, a high degree of resistance to organic solvents, and sufficient translucence so that reagent levels or the presence of filter paper can be easily detected. The unique thread design of the closure allows the vial to be sealed, and opened with an easy 1/4 turn. The quality of the sealing system is such that it is not necessary to tighten the closure with a lost of pressure to achieve a leakproof seal. Polyethylene closure.