The Baader Hyperion 28mm Finetuning-Ring will allow you to easily change the focal length of your Hyperion eyepiece. The finetuning-ring has an outside diameter of 2 & is equipped with a male M48 thread on one end & a female M48 thread on the other. The ring simply attaches to the ring between the front negative element & the main body of the Hyperion eyepiece (not included) & this additional spacing decreases the focal length & increases the magnification. Please note that the finetuning ring is not compatible with the Baader 24mm Hyperion Eyepiece, due to a difference in optical
Specification.