It's a combination of both reflectors and optics. Half the reflector is actually a part of the LED and the other half of the reflector is located in the holder that attaches the optic to the LED board. Unlike bulbs, which have a filament elevated above it's single reflector LED's are placed between a reflector and it’s clear plastic cover, which also acts as a lens. Optics for LED's are multi lens and reflector systems. 3mm and 5mm LED's contain both reflector and lens molded around the emitter element producing a generic flashlight type beam. High Power LED's are used in various applications and this simple generic beam pattern is not adequate for the various applications there are being used in and heat sinking is not possible allowing high power operation. Take your automobile headlight for instance. The beam produced is elliptical and not simply round like flashlights and MR-16 landscape lights. Combining separate reflectors and optic elements into a single optimized package for a tailor-made light system gives the user the most light for the intended purpose at reduced power requirements.