One of the most important areas of race preparation is checking your brush spring tension. We've found that all brush springs vary in strength, even from the same batch, and a major source of armature failure is weak or uneven brush springs. The Fiddlestick will help prevent these disasters. A Fiddlestick will improve your results and help protect your motors. It's made from stainless steel so it's tough enough to take the abuse it will get in your pit box, and then we laser mark it with crisp, clear numbering for easy reading. A Fiddlestick is very easy to use, just put the plunger notch against the end of the spring you want to check and push until you just lift the spring off the stop, (in an assembled brush/spring setup) and then take a reading on the Fiddlestick scale. If the reading is what you want-fine you're set. If not, bend the spring and recheck. Repeat as necessary until you get the desired reading. (TIP: Once you find what spring tension works on your setup make up some extra sets at the same Fiddlestick reading and keep them in your slot spares box in case you need to rebuild a motor at the track.)