The XP 420 Razor is a case where Proform is trying to do too much with this machine.
The Proform XP 520 Razor is a derivation of the Proform XP 420 Razor design. They just added a three-position adjustable ramp to the front of the unit. That might make some people want to buy the unit, but as cheap as this unit is, I would rather them put the extra money into the quality of the machine. Stick with the XP 420 Razor if you want a starter unit or, if you want an adjustable ramp, try the Epic 1200 Pro.