As a life long user of Leica cameras, can someone please tell me what a T to M adoptor does?
Something's wrong here. T-mount lenses are threaded M42x0.75 at the rear (male) end. AFAIK no camera as a T-mount. T-mount's flange-to-film distance is 55.00 mm. T-mount adapters' thicknesses are 55.00 mm - receiving camera's flange-to-focal distance. The OP's adapter should, then, be approximately 55 mm - 28 mm = 27 mm thick. The adapter figured doesn't seem to be that thick. And its female end, shown in the photo, is not threaded M42x0.75.
In the photographer dialect of English T-mount-to-X adapter means adapter for attaching T-mount lenses to an X mount camera.
The adapter shown makes me think of a reverse T adapter for mounting M mount lenses on a T-mount bellows. There are such things, I have several reverse T adapters in a drawer. Or a similar Novoflex adapter for mounting M mount lenses on a some mount or other bellows.