The SIG-Sauer P239 is a semi-automatic pistol.
In the Season 6/NCIS: Los Angeles backdoor pilot episode, Legend Part 2 (episode), NCIS Special Agent Kensi Blye is seen aiming a SIG-Sauer P239 at a group of gangbangers in downtown Los Angeles.
The SIG-Sauer P239 is also the personal sidearm of NSA analyst/NCIS Probationary Agent Eleanor Bishop.
It also appeared in the Season 11 episode, The Admiral's Daughter (episode).
An assassin was seen holding the gun during the Season 12 episode, Grounded (episode).