Nagulagu 20 pcs led Lens 30 Degree with Black Holder for 1W 3W High Power LED Light

These fit well on the 3W star LEDs and do a pretty good job reducing the beam divergence. The edges aren't sealed all that well so you will need to put a bead of opaque adhesive around the edge if you use a filter as I have done - I used them for UV LEDs. Overall they are definitely worth the $.

Works great,

These make great mini-spotlights.