I picked six of these up from the job site today.
I'm not sure what the original purpose was but they were used to hold the temporary fence in place. They are 55# and have a nice carry handle. the T slot must be for what they originally mounted on. I am going to use them on the back of the 195 as counterweight for the loader. I have a 300# steel plate there now that is used for the pickup in winter. These will fit much more compact and can easily be changed up or down based on the need. I plan on picking up 4 more tomorrow.