Mantis
The chamber laser Mantis ships inside its Laser Academy kits, sold on its own for a second caliber or a replacement.
The Pink Rhino is the cartridge already sitting in every Laser Academy kit, sold by itself. It drops into the chamber, and the firing pin sets off a Class 3A red laser at 630-670 nm on each press. There is nothing to switch on and nothing to pair, which is why a chamber laser remains the simplest way to put a visible point of impact on a target.
Buying one separately makes sense in two situations: you own a Laser Academy kit and want to train a second caliber without buying a second kit, or you already own a reactive target and only need the laser. The cartridge is rimless, so a semiautomatic action can be cycled without extracting it, and Mantis offers ten calibers from 380 ACP through 12 gauge, with the 9mm PR-1001 the one most shooters need. Three LR626 batteries ship in the box.
Mantis publishes a specific fitment list worth reading before ordering. Girsan, Hi-Point, Laugo Alien, Tanfoglio, Walther CCP, the Ruger SR series, 9E, LCP, and LCR, and AR-15 pattern firearms are listed as incompatible. The CZ Shadow 2, HK CC9, SIG P365, S&W Shield X, and Springfield Hellcat are listed as compatible but hard on end caps, so expect to replace those sooner. Pistols with a loaded-chamber indicator near 12 o'clock, the Ruger SR series among them, may not work at all.
Add the Mantis Pink Rhino Laser Training Cartridge (9mm) to your build and see how it enhances your platform.