This is the standard telephoto lens available for the mamiya/sekor DTL series cameras. It is the same internal design as the respective lens from the TL series (black and silver design). The lens is also very well built.
The built-in lens hood is very neat and has black flocking material on the inside to reduce flare. There is also an A/M switch for the aperture control.
I haven´t had a chance to test this lens yet, but I will post my findings as soon as I get a chance to run some tests.