They are Original PI legs by the look of it . Didn't the boss legs have plastic bases the could be fitted over the metal foot if required ?
The Canal boxes came with these, which I took off the "new" one I got from ebay a while back. 18mm, 13", they have small plastic inserts for a foot and these cute twist-on mudfeet. They were the only design weakness imo. Neither the small feet nor the mudfeet could swivel to suit a rough or stony bank and both were prone to break. Ok if you always sat on a flat, grass or soft bank .....
I replaced the original legs on both of mine. One has the excellent ball swivel feet which can adapt to all kinds of irregularities, The other has some PI legs with swivel feet - ok, but they only tilt in one plane. Boss also did a platform trolley and footplate which is in the shed. These came with aluminium welded feet.
I'd put these on ebay, but I'm too lazy. If you know anyone doing up a Boss box who might want them, let me know.
Here's one for the north-west seatbox connoisseur. In about 1994 on the cover of Angler's Mail there was a colour pic of some dude fishing a north-west dam. I was so taken with his seatbox, a compact little number with a 4" base, a frame like a piece of modern art, both in fire engine red, and two or three Conti-box drawers/trays topped with a pole seat, I called the paper, got a contact with the angler, found out where he got the box and got the maker to make me one. The angler was Dennis Knight, the maker Stuart Platt, who went on to market completely different but very good boxes, I never saw another like the one he made me. The legs, btw, had a H profile - unique. I wish I'd kept the box.