MusicMedic.com needle springs are heat treated and very rigid yet not brittle. New springs give a faster, cleaner, or snappier feel to the key work of an instrument. These Blued Needle Springs are made from high quality steel with a machined point and consistent, durable finish. These long-lasting needle springs will hold their shape and curve. Available in 19 different diameters, MusicMedic.com Needle springs are strong and consistent. Our 190 Spring Assortment contains 10 of each size spring in a white wooden block. Each spring size is labeled on the block as well as on the plastic tube to keep your springs organized.