Rudy Project Defender RX Prescription Clip works by way of fixing to points on the nose pad inside the standard sunglass lenses. So eseentially you'll be looking through 2 sets of lenses. Your RX clip that will have it's prescription in it and also the outside sunglass lens

Defender RX clip takes a transparent or clear lens and can generally go up to -5.00 combined power. This can change depending on the optical lab and lens material used.

After ordering the Defender RX clip take it along with your Defender sunglass to your local optometrist and they will setup, take measurements for the RX clip and send it to their optical lab. The could take 7-10 days depending who the lab is.

The Defender RX clip can be removed at anytime which allows for easy cleaning of the RX clip and also the inside of the standard lenses on the defender. 

Defender Sunglass with the RX clip can be used for many sports including Cycling, Triathlon, Running