I think I am right here. --- The 4 inch carrot has a body diameter of 0.375. The 4.5 Inch Finesse Worm has a body diameter of 0.3125 and the taper starts closer to the head. ( proportionately less full body, and a faster taper angle ). Compared -- the 3.0 inch skinny carrot has a 0.3125 inch diameter body as well ( a mold I do have that has a pretty good bit of movement ). I have not touched a 4.5 inch Finesse Worm; but it has to have a lot of movement to it based on it's dimensions. The 6.0 inch finesse worm is the same 0.3125 diameter and fast taper so it would have a lot of shimmy as well. My guess is they are designed to be a smaller diameter skinny carrot with even more action.