Groco TH Series Standard Length Bronze Thru Hull w Nut Groco TH Series Thru Hulls are constructed of C83600 bronze and feature a NPSM NPT combination thread. These thru hulls are available in a variety of sizes and come with a nut included. NPSM NPT combination thread C83600 bronze construction UL listed 647B Includes nut Specifications Part Number Thread NPS A B C Weight w Nut TH-750W 34 2.20 0.30 1.90 0.50 lbs. TH-1000W 1 2.85 0.30 2.32 0.70 lbs. TH-1250W 1-14 2.90 0.30 2.62 1.20 lbs. TH-150