ME-IPU: i.Trek Adjustable Sun Visor for Garmin Nuvi, TomTom, Magellan, Mio and other navigation GPS with 3.5 to 7 inch screen
The idea is great, but after a two thousand mile trip across the mid-west in July, we felt it had very limited value and was difficult to attach and keep attached.  Somebody needs to invent one that is much easier to apply and that is two to three inches deep to really keep the sun off the face of your gps.  We ended up using a folded baseball cap with its visor over the face of our gps because it worked better. Save your money.