Skypoint 45 Degree Diagonal has BK7 prism and FMC broadband coating to ensure high quality optical characteristics. The black line design inside the lens barrel can prevent glare and make the image clearer. • Fully multi-coated prisms for superior image fidelity and maximum light throughput;Effectively reduce the light loss of your light during transmission to improve the brightness and color saturation of the image • Correct upside down and left-right reversed image easily;Even if you want to observe wildlife or other scenery during the day; • High quality CNC manufacturing;aluminum alloy housing and stainless steel cover; • Unique brass ring design;Provides a uniform pressure-receiving area when holding the eyepiece; not only is it fixed more firmly;it does not damage your expensive eyepieces • Our correct-image diagonal requires 5/8" more focus travel than typical diagonals;Not recommended for use in Newtonian reflector or Dobsonian reflector telescopes.