Product model: MINOLTA MF MC FISH-EYE ROKKOR-OK 1:2.8 f=16mm ，only for MF 16 2.8, not for AF ,if you need AF 16 2.8 connect me 

Usage: press down or lift up while rotating

Origin: self made，made by 3D print

Material: soft rubber, no damage to the lens

Note: The lens of the extender is so protrusive that general cap is unable to cover it, therefore a higher cap is made，although the appearance is a little rough, the material is sufficient and it can stuck the lens steadily，any question connect me ,no retrun