Bests & Worsts Reviews from Amazon

I got this with the intention of using it to cut through a "kryptonite" U-shaped bike lock. Since it comes with just a grinding wheel, I bought the 5-pack of cutting wheels that Amazon notes are frequently bought in combination with the grinder. Unfortunately I did not heed the advice of another reviewer, who pointed out that the grinder's instruction manual states that a ***Type 1 disc must not be used.*** Instead only a Type 27 disc is allowed, for safety reasons. It has to do with the way the wheel sits within the guard housing, apparently. Unfortunately the frequently bought 5 pack of wheels does not give you a clear picture of the wheel and there is no mention of the "Type" number in the description. Now that have them, the wheels are in fact marked Type 1. So just now I ordered a Type 27 cutting disc. It is easy for the uninformed (such as myself) to assume that since the Type 1 and Type 27 cutting discs have the same 4.5 inch diameter and the same 0.045 inch thickness then they must be identical in size. However after some research I learned that the Type 1 is a flat disc, whereas the Type 27 has a raised portion at its center, which causes it to sit lower in the safety guard.