Released in 2004, the Grind Master was the fourth release in the Project Red Alert series (formerly named the Redline series) by YoYoFactory.
The Grind Master kept the smaller body shape of the Grind Monster, but also boasts a high-tech teflon-coated finish, dubbed "Slick Skin". The Grind Master was the first yo-yo ever to include this type of finish, which would be later implemented in certain editions of the F.A.S.T. 401k. It was also the first yo-yo to come standard with recessed response pads.
Between the retail version and a special 2004 Worlds edition, a total of about 155 yo-yos were produced.
In the below photos you'll see that this used yo-yo has one red rubber pad and one thick Dif Pad.