This adapter lets you turn any manual focus Tamron Adaptall, Adaptall-2, or SP lens into a fully functional M42 standard screw mount lens. Automatic aperture control is retained.
When you use this adapter in combination with the Mamiya P-mount adapter, you can basically fit any Tamron lens to your Mamiya NC series camera.
As of today, Tamron still produces almost a full range of manual focus lenses for the Adaptall-2 system ranging from a 17 mm super-wide-angle to a 500 mm telephoto lens. The SP lenses are renown for their excellent quality.