I wouldn't call out any difference between tunable or adjustable, both are adjustable, but some are detent secured and some are lock screw secured. JP sells both types. Most of mine are lock screw secured, but I do have two of their detent type. All of them work, and it's not much of a challenge to adjust the gas to put on my can - I simply file out the edge of one of the handguard holes or drill a hole in the side of the guard above the set screw on the side. Easy enough. Detent types are easier. Some have knobs for adjustment, I'm not a fan.