New and in stock at RSOV.com is this China-Made CEU Magnifier Angle Scope with a QD mount and they're selling it for US$79.99. Helpful for shooting around corners and obstables... "Mounted behind a sight or scope, allowing the player to safely look around either right or left-hand corners, up staircases or down tunnels from almost any angle. Since it does not affect the sight’s point of impact, it can easily be passed from one player to another using the company’s TwistMount. The compound optics contained in this gives the player a true image, not the distorted mirror image found in some reflective devices currently being offered on the market.

It can be rotated."