Just for Information. The pad is fitted by removing the old pad off your shottie and screwing 2 nipples into your stock, included with 2 screws, also included.. You then push the pad on over the nipples and a simple push clasp holds it in place. I believe they do a number of different size pads. Hope that is of use to some one even thoug I haven't described it very well. There is no sanding or anything involved..
I can speak in-depth and with great knowledge about most subjects until some bugger who actually knows what he is speaking about opens his gob .
Don't know if this is helpful but having just replaced the butt pad on my SP I now know that the sporter & field stocks are slightly different - sporter 53/8" long, field 5" long.