This is an adjustable focusing extention tube that works smoothly. ProOptic extension tubes are the first set allowing to adjust the distance between your lens and camera's body in smooth and easy manner. Focusing distance may be adjusted between 46 and 68mm. This will enable you to easily set the desired focus distance. The tubes function exactly like zoom lenses. By rotating the tube, you can increase or decrease the distance of your lens.
May be Meike brand