The Grind Monster was the second yo-yo in the Project Red Alert (formerly Redline) series by YoYoFactory, released in February 2004. It is limited to 300 units.
The Grind Monster was the follow-up to the Grind Machine, and featured a slightly smaller diameter and lens caps attached directly to the aluminum halves. It also featured the "Gap Gadget" system, which allowed the user to adjust the string gap width by simply twisting the body halves, similar to yo-yos such as the F.A.S.T. 201.
Similar to the Grind Machine, it comes included with three sets of response pads, each made of a different material and with a different level of response.
A production error while manufacturing one of the Grind Monster yo-yos resulted in the introduction of the magenta-colored and very limited "Grind Mutant".
In the below photos, you'll see that this used Grind Monster has one cork pad and one thin Dif Pad.