The PP-90M1 (Russian: ПП-90М1) is a 9x19mm Parabellum Russian submachine gun developed by KBP Instrument Design Bureau in the 1990s. It features a 64-round helical magazine, and other than sharing a manufacturer is unrelated to the similarly named PP-90M.
The weapon is not to be confused with the PP-19 Bizon, which has a similar name and underbarrel helical magazine design, but is completely unrelated.
The PP-90M1 is most commonly known for its 64-round helical magazine. The weapon can also use a 32-round box magazine with the help of an adapter.
Instead of a charging handle, a sliding piece that is placed above the muzzle is used to charge the weapon instead.