The NANRIC Buttress Wedge was designed to support the flexible buttress and not wedge the heel. This works great for horses with a negative PA and 15 - 20 mm of sole under the apex. 
Note: Horses must have adequate sole to properly use the Buttress Wedge. You may wish to use a Full Rocker or Rocker Rail Shoe as the initial shoe to quickly gain sole mass and then apply the Buttress Eggbar with the Buttress Wedge.