Adapter Saiga 9 and Saiga 410-04 (manufactured from 2016) with horizontal slot for buttstock lock. Mounts to the standard stock place, then tube screwed in to adapter and telescopic buttstock mounts on this tube. Tube is secured by retaining washer and nut with special buttstock wrench. Adapter is made from steel, weight is 162 g.
Adapter for tubes with thread 1-3\16-16UN