John, i would suggest this Viridian laser
budsgunshop.com/product_info.php/products_id/142193/viridian+912-0008+e-series+laser+sight+5mw+red+laser+with+635-650nm+wavelength+25+yds+day+1+mi+night+range+black+polymer+for+gl ,
Remember, your holster must be made to accommodate the laser.
Stay safe & have a great day!

I suggest clicking the link below which will bring you to all available here on Bud's. Then, it'll be a matter of preference.
Good luck.
budsgunshop.com/search.php/q/laser+sight

John, personally I'd go with a viridian laser that fits on the trigger guard. Here's a link to one of interested.................. budsgunshop.com/product_info.php/products_id/142193/viridian+912-0008+e-series+laser+sight+5mw+red+laser+with+635-650nm+wavelength+25+yds+day+1+mi+night+range+black+polymer+for+gl ........................ Hope this helps.

Hi John and welcome. The ArmaLaser is a popular option : https://armalaser.com/TR22G-Green-Laser-for-GLOCK-1719202223243132343537384445-All-Gens-with-Rails-will-not-fit-45-ACP-and-10-mm-models_p_893.html ----------- Holsters for concealed Carry for the laser sight : https://armalaser.com/glock.html - Cheers and stay safe!