'T' Handle Mixture Screw: Making minute adjustments on your FCR carb can be a challenge as the original fuel screw is inaccessible without burning your hand and or removing the carb completely, especially on bikes with electric starters.. This handy little T-handle fuel mixture screw allows you to make minor adjustments while sitting on your bike, if necessary. Since most carburetors are sensitive to altitude and temperature changes this will save you hours of time and frustration. It’s even beneficial to make adjustments as your air filter starts to get dirty which affects the mixture of your bike. A simple correction and away you go. Fits most FCR carburetors