The Meta Pro peep has a patented convex interior diameter maximizing the field of view in low light. The convex interior also provides a perfect circle as the peep begins to tilt – no more looking through an oval. The string groove is also convex, creating less surface area that the string actually contacts, reducing string wear significantly – so much so that the Meta Pro has a NO-CUT GUARANTEE. The Meta Pro comes in Black, Purple, Pink, Green, Blue, Red, and in 3/16″, 1/4″ and 5/16″ sizes.