Storz Head component shall be forged from Alloy 6061 aluminum and heat treated to T6 temper. Adapters and components meet the requirements of NFPA 1963. Locking Storz are only available on 4, 5, and 6 inch. Locking springs prevent unintentional disconnects. Locks are stainless steel.
Note - 3 inch NH / NST is very rare and is often confused with 2 1/2" inch NH / NST which is very common. If you have a fire department connection (FDC), hose coupling or an adapter check the female coupling for stamped numbers and letters. Most 3" hoses use 2.5 inch NH / NST couplings. The most common fire fitting thread in the United States is 2 1/2 inch NH /NST.