3hounds: Sorry for any confusion, the subject is the S&W SD series.

The only S&W guns they sell springs directly to the consumer are for the full size M&P. You can check their website for the other brands they sell on a retail basis-

Integrated Systems Management Inc.

and select "Products" to see what they support to end users, or read this section of their response:

"We have never sold these springs for use in anything other than the full size pistols or told anyone that they work in anything but the full sized M&P pistols."