I think this is what i have but it is not enough support to keep the pants from cracking. The wheel collar slips over the axle and sits inside the pant. 2 screws from the outside of the pant go into the holder collar which is on the inside of the pant. I am on a grass field but have not had a rough landing and the stress from the limited support has allowed the pants to start cracking.

Found the sig item...different from what I was talking about and not sure how it's used....here is a pic.