Milton (S-614-6) 3/8" NPT Brass Compressor Tank Drain Cock - Steel Handle - Box of 10 NPT: 3/8" national pipe thread. USE: To replace old or damaged drain cocks on compressor tanks. DURABLE: Brass body and steel handle. RELEASE: Air from tanks before replacing drain cock. Turn handle to drain water. Close when water is drained. OTHER SIZES OFFERED: Milton also offers drain cocks in 1/2", 1/4", and 1/8" NPT sizes. Milton is your number 1 source for Quality Air Accessories Since 1943 Milton has been producing Quality Air Accessories Milton covers automotive, industrial, hardware, agriculture, heavy-duty fleet and MRO markets