Miranda Kettlewell donates a Fleeceworks shimable saddle pad.  Used once.  It is a FW-6/D Large.  There are four memory foam inserts.  

The Fleeceworks™ Perfect Balance  Therawool  Half Pad enables you to discreetly cushion your saddle and make temporary fit adjustments as needed. With an anatomical design that allows space for high withers, this pad features internal pockets designed to hold removable inserts, with four inserts included. The inserts are made of light, anti-slip Memory Foam visco elastic and effectively mold to your horse's body for a perfect fit.