Free: Contests & Raffles.
Or what about the Bushnell?http://www.amazon.com/Bushnell-Banner-4-16x-Illuminated-Reticle/dp/B004NK8SFM/ref=lh_ni_t?ie=UTF8&psc=1&smid=A30DGGRQPDAP9Y
It's how high the rings are off the rifle. If you're going with a 40mm objective lense, go low.