I've switched all my 1oz tanks to these. You don't have to block the nipple, only one of them is "live" you have to drill the second one out to use it. They are lighter than the sullivans and the clunk works much better. I have had zero problems with them. Using them on a couple of backplate pressure motors too. I find they are much easier to mount in small spaces and the slant tanks are a pain with the tubes coming out at funky angles. For motors without a muffler I just run the vent hose up to the top of the cowl and use a small landing gear strap to hold it and cut the end at a slant.