CHIHIROS RGB 60
Although this fixture is a little more expensive than your average budget fixture (Beamworks/Finnex), it makes up for it in quality and construction. The top of the fixture is subtle heatsink which help dissipate heat. It outputs higher PAR values than the 24" Finnex FugeRay Planted+ and 24" Beamworks DA FSPEC and is adjustable in length up to 30" (can extend even longer but the metal rods will bend) and height up to 8.5".
PAR tested using Seneye PAR meter unless otherwise noted in the notes section. Testing process is documented here