The RX4 is still being worked on (rail issues) - the RETRAXPROMX is definitely worth the extra cost! - Lifetime warranty on a perfectly built cover..
You've probably seen other threads showing half opened RamBox lids. This happens because the rubber "seal" that runs the length of the Retrax rail overlaps the lid by 1/2-3/4" and binds when you try to open the lid. Its a very shortsighted and negligent design and true for both models.Can you elaborate on what modifications are required to the factory rails to allow the RamBoxes to open properly with the Retrax? Also, is this true for Retrax Pro?