Removable TFE delivery stem virtually eliminates the breakage normally associated with standard glass stem stopcocks. Made entirely of TFE, the stem attaches directly to the glass thread without o-rings or other gaskets. Glassware equipped with this stem can survive repeated forceful strikes to the stem without breakage. They have also been dropped from a height of 3 ft without breakage, so long as the initial impact was received by the TFE stem.