I don' t think it is really needed, I think is was somthing to try and hype the bow line. On 70lb bows with the roller guard they have 60lb limbs on them. If you take the guard off and check the draw weight you will get about 8-10lbs less. When you draw the bow with the roller on as you draw the bow it preloades the limbs to get to the 70lb draw weight, My only ? is will it start causing limb failers after the bow gets up in years, because of the added stress put on the limbs from preloading them? Only time will tell. I have also seen 4 mathews came into the local archery shop in my town that the string and cable jumped the track on the roller guard and got chewed up, one need new strings and cable and the others just needed reserving. There is one advantage I can see to the roller guard is it should produce a smooth draw because the cam and the limbs are both working to add the weight to the pull. They may be more advantages but I don' t know what they are.