I just got the 5 Smoktech Airflow Controller rings I had ordered in the mail. Here's my review of this product: Contruction: - One hollow bottom ring with, diam. 20 mm, with a 510 jack at the bottom, a 510 socket at the top, and a larger threaded post (not sure about the size of the thread, I haven't measured it. All that matters is that it's not eGo, regrettably). - One top ring that screws onto the larger threaded post. - A floating, electrically insulated center pin. Use: - Screw the thing onto your battery. - Screw the clearo onto the thing. - Screw/unscrew the top ring to adjust the airflow (in theory) or to bring it against the bottom of the clearo to stabilize it in the 510 socket (in practice). Efficiency: - None. As an airflow controller, it doesn't work. - The top ring's edge is smooth instead of being serrated, which makes adjusting it difficult. Fortunately, since adjusting it doesn't do anything, it doesn't really matter. - Fantastic product to preserve your battery's 510 socket. Screw it securely onto the battery once, and wear out its 510 socket instead of the battery's. To be honest, that's why I bought them: I swap clearos several times per day, and I'd rather replace a $2 ring than a $100 mod when the 510 threads go. Highly recommended as a 510 thread protector ----- EDIT: I cut serrations around the top ring with a triangular needle file. That makes it a lot easier to turn. If you're handy with a file, it takes 10 minutes and it makes the thing look good too. Check it out: EDIT 2: when I say the thing doesn't work as an airflow controller, I should perhaps be more specific: - With clearos equipped with vent channels at the base, like the Innokin iClear 30, it plain doesn't work because air gets through the vents no matter what. At best, you feel a very slight restriction when the ring is all the way up. Not much to write home about. - With other clearos like the Vivi Nova, when the ring is all the way up, the air flow stops completely. Undo the ring 1/4 turn and the air goes through unimpeded. Anything in between is very hard to adjust, and in any case, the top ring is loose enough on the base that, if it's that close to the clearo, the mere act of sucking hard on the tip will draw it upwards and close the vent hole anyway. The top ring *is* useful, to prevent the clearo from rocking from side to side and damaging the 510 thread. But as an air flow controller, it doesn't cut the mustard.