Accurate to ±1% of rated BAF Gives a narrow-sharp image for good results in dense timber Supplied in leather case Clear glass prisms perform satisfactorily in most cruising conditions Our most popular prism shape. Accurate to ±1% of rated BAF. Gives a narrow-sharp image for good results in dense timber. Clear glass prisms perform satisfactorily in most cruising conditions. Amber glass prisms prove superior when cruising is done in low light, hazy or misty conditions. 20 mm x 40 mm. Supplied in leather case.