From the units which I have ordered and received, my findings have been inconsistant. The true 50 does not, but the true 30, untrue 50, 30, 20, 10 and 5 do. On these ones there is a slanted piece of thin glass, opposite the photodiode. The labby 35 doesnt have, nor does the 100mw. It seems that they are only installed on units to which it serves a function. ie it feeds the photodiode a percentage of the beam for the APC. So basically any of the lasers ive received from them have only had poor ir filtering, only on APC modules. The filter is only about 1/4mm thick, but it does make a bit of difference. The best solution I have found for ir filters, is nova. As they are nice thick filters designed for both types of IR emmited by green lasers. The only challenge with the nova filters, is that they are huge. Out of the box they wont even fit in the labby's. And cutting them can be really trickey, without scatching them that is.