Uxcell a15082600ux0938 Push in to Connect Fittings Pneumatic Flow Speed Control, 6 mm Tube, 5 Piece, Metal, 0.24"

Used these in a jump scare prop for Halloween where a giant spider would jump forward toward the kids coming for candy. It worked pretty well, except the first test had enough pressure that it snapped the aluminum rod it was on. Decreasing the pressure made it jump out too slowly (or not at all), so adding one of these to the return was the solution. They offer a good range of variance, and are easy to install. Would definitely recommend, and will purchase again when I run out.

some of the needle valves leaked slowly or would not shut off completely but they worked for my application. they are not the high quality of legris or parker

Works great