Description The OG Base Kit 3.0 provides a compact, universal digiscoping system that works with your preferred phone case and automatically centers your camera with your optic after setup. The low-profile MagTab attaches to your phone with included alignment assistance, while the custom-fit Optic Spacer and Adapter Ring create a secure, repeatable connection for faster photo and video capture in the field. Optional components include a protective cover and a specialized Leupold MK4 and Gold Ring eyecup for compatible optics. Sizing Spacer Size Eye Piece Outer Diameter (inches) Alpha 1.55 - 1.64" Bravo 1.65 - 1.74" Charlie 1.75 - 1.84" Delta 1.85 - 1.94" Echo 1.95 - 2.04" Foxtrot 2.05 - 2.14" Gulf 2.15 - 2.24" Hotel 2.25 - 2.34" How to measure: To measure your spotting scope or optic eyepiece, place a tape measure across the widest point of the outer eyepiece housing. Measure straight across the center from one outside edge to the other to determine the eyepiece diameter. Specs Includes (1) Adapter Ring - Universal magnetic ring for fast MagTab alignment(1) Optic Spacer - Available in 8 sizes to fit your eyepiece(1) MagTab - Low-profile phone plate secured with 3M adhesive (included)(1) Alignment Tool - Centers your phone camera for precise installation Manufacturer Warranty Lifetime against manufacturer defects