The Shelby Division of Copperweld, in Shelby, Ohio, used this time recording punch clock. The numbered wheel can be rotated, which activates the time recording mechanism, causing the employee number and time to be printed on paper tape fixed to the drum at the rear of the mechanism. The clock is an electrically activated slave unit connected to a master clock. Such time clocks both regulated employees' workdays and helped insure accurate calculation of their pay.