Prusa Y belt tensioner pad

This is an accessory to the Prusa Y-axis belt tensioner here: http://www.thingiverse.com/thing:10274
Some setups also use this tensioning mechanism for the X-axis.
The trouble is that if you over-tighten the tensioning M3 bolt (or simply over time) the screw will poke all the way through the timing belt and ruin it. This piece acts like a padding and evenly distributes the tension across the belt surface.