AUTO Mamiya Sekor TL/DTL Series
" The lenses were made for the Mamiya 500 TL, 1000 TL, 500 DTL, 1000 DTL, and 2000 DTL.
The lenses for the TL series originally had a silver aperture control ring and a silver front lens tube, the ones for the DTL series were all black. Functionally they are identical (mostly auto aperture) and compatible with most M42 cameras. A few of the lenses are slightly different between the TL and the DTL series. "