"This is a good adaptor. There are no gas leaks if you tighten it and it is very durable. It may seem expensive, but if you buy one it will save you lots more money in the long run. I have gone through 2 propane bottles using this ($6), if I had used green gas it would have cost me around $40-50. Make sure to apply silicon oil on the opening of the propane bottle before you attach the adaptor; do this every 5-6 magazine fills. Make sure you use 100% silicon oil, (AMS sells it pretty cheap) if you use anything else like WD-40 or Hoppes 9 your rubber O-rings will melt and you will have to replace them. It will also destroy the O-ring in the propane adaptor rendering it useless. I would recommend this adaptor to anyone who owns a green gas airsoft gun or a 40mm grenade launcher. "