The Spectre M4 is a submachine gun manufactured by SITES (Società Italiana Tecnologie Speciali S.p.A.) that chambers several different calibers. These calibers are the 9x19mm Parabellum, 9x21mm IMI, .40 S&W, and .45 ACP.
The Spectre M4 is categorized as a submachine gun in the Rainbow Six universe.
The SM4 CQB was designed in the mid-1980s with a focus on bringing a lot of power to bear in CQB situations. A recoil-operated automatic firearm, it has a unique trigger design that more closely resembles that of an SMG than a pistol.
- "An Italian submachine gun designed in the 1980s for counter-terrorism and law enforcement agencies, with a pistol trigger for ease of use. Normally the SP M4 uses the High Capacity Magazine or Suppressor attachments."
— In-game description
The SP M4 is a weapon featured in Tom Clancy's Rainbow Six: Lockdown.