4.5mm

Air Pellet Gun 350-300+ FPS 4.5mm .177 Caliber Pistol Gun + Pellets + Laser

Winchester Pointed Pellet for Use with Air Gun Ammunition .177 Caliber, 500 Count

PH0911 PEDERSOLI GUARDIAN 209 DERRINGER 4.5MM

Bb Gun Steel Ammo 4.5mm Stainless Steel Balls - China Steel Ball, Valve Ball

Chiappa Rhino 60DS 4.5mm Airgun CO2 Revolver Gold Edition

4.5 mm underwater pistol SPP-1M

Pilot Parallel Pen Set with Cartridge - 4.5 mm

4.5×26mm MKR - Wikipedia

Umarex XBG 4.5mm BB Pistol - Black (.177 cal Air Gun), MORE, Air Gun / Pellet Gun, Air Pistols / Hand Guns - Airsoft Superstore

Colt Commander 1911 Airgun Blowback Metal Frame (.177 Cal / 4.5mm BB) – MCS

Crosman MK45 4.5mm Airgun Pistol