This is a good reg. Made for markers like the phantom, carter, trracer and other pumps, the reg allows regulation of co2 by directly screwing into the asa. It's incredibly tiny and suprisingly consistent. It is a branch off of the CMI reg. On my trracer, it improved accuracy and consistency by at least 10 fps. Now my variation is down to +-10 fps
If you can find it, buy it. I give it a 10 because it is the best I have used in it's category.