Caliber: 9mm Sound Reduction: 34 dB Length: 6.875'' Diameter: 1.375'' Materials: Aluminum Mount: 1/2-28 Includes: (1) Suppressor Direct Thread Piston: (1) 1/2-28 The Stealth is full auto rated and user servicable and adaptable to an incredible number of platforms including .357 and 38spc rifles. The optional adaptors are as follows (1/2x28, 9/16x24, 5/8x24, M13.5x1LH, SIG MPX, UZI, Scorpion, and MP5 Tri-lug) Sound reduction: 34 dB