These are weights that have a hand grip cast in.
They're used on the front bumper of a tractor to counterweight any implements on the 3PH.
John Deere's smaller suitcase weights go about 42 lb (19.1 Kg).
As far as being universal, the bracket that holds them on the front bracket appears to be specific to a brand. However, it appears one could rig up an adapter fairly easily.
The picture attached shows one type..I've no idea which company this one was manufactured for, but I know it's not the Deere design.