They were introduced as the "Schwinn-Approved Professional series of spoke wrenches" in a December 1971 Schwinn Reporter article titled "New Tools Ready for 1972". The bodies were chrome plated cast bronze and the replaceable inserts were made from "the highest quality tool steel". They were available in three sizes (.080, .105, .120) and cost $4 each. The inserts were also sold separately for $1.60 and the body alone was $2.90. The article also stated that "The Professional series of spoke wrenches was developed in cooperation with the Schwinn manufacturing division, and these are the same spoke wrenches that are currently being used in the factory wheel department and by the inspectors on the Schwinn assembly line".