Loose Risley Prisms (Pair)
Item #: ARPHH20
Fits into the standard 38 mm eyewell of the Bernell-O-Scope or any standard trial lens frame. Each prism yields 20 PD for a total of 40PD. Now you can set any amount of BI, BO, or vertical prism into the stereoscope to do training procedures. May be used for distance training by removing the cardholder.