14 mm CCW / 1/2"-20 UNF, for airguns up to 6.35 mm (.25), length 200 mm The versatile SD4 suppressor is designed for airguns with calibers of up to 6.35 mm (.25). Especially at higher energies, the SD4 offers excellent sound suppression due to its 6-chamber design and a precision CNC-machined aluminum body, reducing the sound by 25 dB. There is also a noticeable difference in sound suppression when used with airguns in the 4.5 mm (.177) and 5.5 mm (.22) calibers. To maximize compatibility, the Umarex SD4 comes with two thread adapters (14 mm left-hand and ½″-20 UNF). Technical data Caliber 4.5 mm (.177) Pellet 5.5 mm (.22) Pellet 6.35 mm (.25) Pellet 4.5 mm (.177) BB Barrel thread 1/2"20 UNF and M14x1 CCW Length 200 mm Weight 190 g