The Reactor by Custom Products is an all-aluminum miniature yo-yo, which was very popular in the late 90's. The butterly-profiled Reactor preceded the Chain Reactor and was originally offered as a fixed axle yo-yo using a replaceable composite-material sleeve on a metal axle (similar to the original 1984 Silver Bullet). Eric Wolff devised a way to replace the fixed axle sleeve with a ball bearing and response pads made from Rubbermaid no-slip bathtub tread strips and gave this new transaxle design back to Custom to be used in future production.