1/2 x 28 tpi to UZI M26 x 1.5 If you have a 1/2 x 28 tpi threaded barrel and want to use an UZI suppressor with M26 x 1.5 threads, this adapter will provide the conversion without the expensive cost to replace or re-thread the barrel.TROS adapters are manufactured from 300 series stainless and are black oxide coated. They are guaranteed to be concentric.