New ideas in rigging terminal ends are slow to happen,often its just a change to a design trend already in existance but I think Gibbs T Ball was a first,its a favourite of mine,super strong and very easy to remove the rigging stay at the mast end with out tools.
The T Ball end came out some years back now,it requires a swage tool and locks into a cast 316 stainless steel backing plate that is fitted inside a slot in the masts side wall,the plate is held inplace with monel rivets,when the T Ball end is then installed,it anchors the plate and itself to the mast,simple but secure.It also allows movement,which lines the stay up to the lower rigging screw or turn buckles prefectly.
Also made by Gibb,a super slim rigging screw,this size will suit a set of lower shrouds or stays on a yacht around 37ft long ( 12meters) the style is elegant but when final tightening of the screw was being made it tended to open out in the center slot some.With a Gibb T Ball at the mast end and a Gibb rigging screw at the deck level this was a very neat set of fittings,circa 1980 I would guess?
R McB