These are precision machined, extended fuel / air mixture and throttle stop screws for your Amal concentric (not monbloc) carburetor. It is great to be able to make fine tuned adjustments on your carb by turning these with your fingers. Perfect for use on any Amal-equipped motorcycle such as your Triumph, BSA or Norton. Included are one air / fuel mixture screw, and one throttle stop screw with o-rings, good for one Amal carburetor. If you have a dual carb setup you will need to purchase two kits!