I have a helmet with factory sewn on OD 7 straps. Swivel bale, front seam, stainless rim.
It has a flat black painted steel buckle and has a green painted steel T1 “J” hook. To me it is missing its ball joint as it is very difficult to hook and unhook it to the buckle.
So does this mean that perhaps the first T1s were green and this may be a early mixed set up using up the remaining black buckles, I shall let you decide on that one Andy.