35.6mm Secondary Optics (Plastic / 5-Pack)

Pros: Shallow, space-saving Large diameter with wide lip that can be trimmed

Cons: Cavity too deep for many types of LEDs
All 5 optics were scratched because they were packed without padding in a small zip lock bag
Large flat bottom that is only good for revealing the type of LED installed
Sides at wrong angle; does not seem to reflect well

Other: I was looking for something with more water and impact resistance than a lens/reflector combination, but the poor light output made me put the reflector back in.
This optic would be much better with a shallower, dome-shaped cavity and a narrower, parabolic shape without the flat bottom.

Pros: This is an good, low cost plastic TIR optic. The counterbored hole allows for the Cree's metal rim to align perfectly with the optic.
Unlike the previous reviewer, none of my optics arrived scratched. DX packed each one individually in a small ziplock bag, then rebagged all five in a larger ziplock bag, followed by a bubble envelope for shipping.
I measured the beam's spot to be about 6 inches wide at one yard away. This equated to about a 10 degree spot beam. There is also a secondary flood/spill with a 90 degree beamwidth. The beam is not perfect, but it's OK. The flood is a bit ringy, and the spot does suffer from some purple fringing.

Cons: None. It's perfect for my application.

Other: Get this and let your modding imagination run wild!

Pros: Individually packed so they arrived unscratched. They fit on CREE perfectly.
The beam is very tight, the spot of maximum brightness is about 8 degrees from the main axis then there is some dimming out to some 12 degrees and thereafter rapid dimming. There is not much spill beam at all.
Efficiency seems good.

Cons: Beam is not perfectly round.
Not much spill beam. Could be pro depending on application.

Other: Very cheap optics that does what its supposed to.

Pros: I bought this because I wanted to test some TIR optics to check out the beam profile for myself. And they are (for the pirce) of very high quality compared to some german produces ones I also bought elsewhere that cost more for 1 pce than 5 of these. Get me right - these are not as hogh qualiity as the german ones, but they are 1/10 the price! And thay are close. Maybe 85-95% depending on which one of the five I got that i have used.
Cheap enough that I was unafraid to grind some of the bottom away on two of them to get a even narrower beam with an XML led. Worked great.

Cons: There is some variation within the batch of five that I got. You cannot see it with the naked eye before you put them in front of the same led running on the same battery and lining it up the same. Some of it is due to small variations in the thickness of the outer rim. I was able to confirm this with a micrometer gauge.
You have to grind a few millimetres away of the bottom or "throat" where the led goes to get a perfect narrow beam with the XML leds that I tested with.
Seems to make the beam color colder.

Other: At the price point you might get this even if you are just the slightest bit curious about whether you like the beam profil of a TIR light.
Great for really short XML lights because of their short size. Does the same job as a 40 - 50 mm deep reflector does, especially if you carefully grind a few millimetres off the throat and is really careful when lining it up in the flashlight body.

Pros: More than 99% of the light that comes in , comes out. The throw can be influenced and even can be made very narrow, like a good reflector does, but without the same spill, so more energy can be put in the throw. When you want to make an IR thrower for Nightvision , this optic comes in handy, even 1024nM is no problem

Cons: PMMA can easily be scratched.

Other: When you build your own flashlight and other lightgear, these optics can become a favorite part, Seoul, lumileds, cree T6 they al can be used with this unit, gives much spot and less spill than reflectors do.