. Grease-free PTFE stopcock. Temp. range: -18 to 60°C. 0 to 5 mm flow cross-section. . . Sigma-Aldrich Z405698-1EA J. Young General-Purpose Stopcock, Right Angle, 8mm Side Arm OD, PTFE. Country of Origin : United Kingdom. Part Number : 1190Y62EA. Pack of : 1.