One of the posters on here asked how we plan to mate One and Only next year and what we have found out so far. For us he has worked best on smaller framed cows. We used him on both large and small framed cows and he fooled us this first year!!! Yes the calves are not big framed when they are born and the ones out of smaller cows were plenty small. So at breding time we figured he needed more gas so we bred him to larger cows. About mid summer they all took off and really grew (now we were happy with how they were doing before then as they were getting thicker and deeper), but at about 4 months the frame kicked in and the ones from the larger cows got alittle to big to be concidered for show steers. Granted they were hot items at the sale barn and you know we still live in the real world, where not all of them make the show ring. So even though we did not get the big preimum for them they still got the buyers at the barn excited. Also we did find he worked very well on carrier cows,,yep bred him back to HW daughters and grand daughters,,it worked, but birthweight went up on dirty cows. So for us it going to be moderate to smaller cows WITH some rib, both clean and carrier, not to worried about thckness as he adds plenty and the soundness needs to be watched but is not a big issue. And just a footnote, if hair is an issue he need to be used on a cow with average to good hair on her past calves. Hope this helps and remember this is just the way he worked for us,,,,your results may varry!!!!!