We used him on a frame score 4.5 to 5 cow that is a who made who angus. She had a 68# heifer unassisted. This also was her fourth calf. she only struggled once with a 130# that got stuck on its way out. The heifer is a baldy and is very fancy. We took her to a couple of shows and the one comment they always give us is she is very feminine and clean made. We gave Amazon a shot on the same cow this year. I plan on using Macho again.