Astromania Alignment 1.25" Next Generation Laser Collimator 2" Adaptor for Newtonian Telescopes
Amazon.com : SVBONY SV121 Red Laser Collimator, Adjustable 1.25 inch Collimation Eyepiece, with 2 inches Adapter, Telescope Accessory for Newtonian Dobsonian Marca Telescope : Electronics