This PYREX® stopcock is T-shaped, has T bores and is ideal for gas analysis manifolds. It has a No. 2 ST glass stopper plug with 2mm diameter bores. Stopcock sidearms have an 8mm O. D. For additional strength, sidearm seals are heavy and uniform. Takes retaining clip no. 4. For replacement retaining clips, see Cat.No. 1-7280-4CO.