MV2-10 Shore A is an ultra-soft silicone, to fill the hollow.

MV2-10A Remplissage-Packing is an ultra-soft silicone packing with a firmness of 10 Shore A. It is ideal for filling and sealing hollow points between a shoe pad and the sole.The light firmness of the silicone is also ideal for avoiding any pressure points under a highly sensitive sole. Not recommended for V-notched pads.
Optimal results with the MV2® pads.