Mdevices Stop Cock, Box of 50 - All Sizesm devices 3 Way Stopcock with 15cm, 25cm, 50cm, 80cm or 100cm Standard Bore Extension Set is lipid resistant. Flow directional arrows are visible on the tap to assist the clinician with flow direction. Male luer lock with rotating collar and Stopcock has two female luer connections with caps. IV extension sets with Stopcock should always be primed prior to connecting to a peripheral catheter or access device on an IV administration set.