Vivitar 2X Teleconverter for Mamiya RB67 medium 120/220 format camera.  Lens is clean with no fungus or separation of elements.  Includes both front and rear lens caps and user manual instruction booklet. Doubles any RB67 lens by a factor of 2; example: 90mm appears as 180mm. Light loss through the teleconverter is a constant two stops; example: f5.6 becomes f11.
Automatic action couples lens f-stop to camera body which allows full brightness for focusing yet stops down lens prior to shutter exposure, this action works smoothly without any sticking or hesitation.  Black metal body, made in Japan.