Here is a link at Cabela's for what you want.
http://www.cabelas.com/wader-accessories-studded-replacement-felt-soles-3.shtml
I have re-soled my Simms Freestones a couple of times but not with studs just regular felt. If you follow some advice you can get a good bond. I buy a couple of tubes of Barge cement or any good waterproof contact cement.
You have to completely remove any old felt. Then liberally apply a coat of cement to the bottom of each boot and the back face of the felt. When both are dry apply a second coat to each but this time when they are both tacky (no wet cement) I carefully position each felt onto the boot. You want to be in the correct position because when you put the pieces together they want to bond, and stick together, with real permenance.
Then I get a rubber mallet and beat the heck out of the felt, I pound on it a good couple of minutes - I think it improves the bonding. Then I take Duct tape and liberally wrap the tape over the boots and felt, spiraling over and over until the felt is covered with tape.
I leave it taped until the next day then remove the tape and get my electric knife out and trim the excess felt right to the peripherary of the sole and I'm good for another couple of years. I don't use studded felt as I'm convinced the grating of the studs on rocks in long flat pools scares and spooks the heck out of rising trout. Also they make a racket in my drift boat and I tell guys "you want to float with me no studs".
It was kind of funny how last year Simms was advertising all their new Vibram soled wading shoes and now this year I see in "The Trout Shop" catalog where Simms is back to felt. Ha Ha, so much for environmentalism and concern for our waterways! It's all about money.
Regarding the Vibram soles on some wading shoes; I went to Alaska in August and knew before hand that felt soles were prohibited. So I went and bought the mid price point Simms shoe with the Vibram soles and a set of the sixteen triangular shaped screw in carbide cleats and have been surprised at how well they have performed. Now I've not tried them in the Susquehanna yet or in the upper EB of the Delaware which is notoriously slippery so don't know how they will perform on a really slippery river but so far I really like them.
PS - I have another pair of regular Simms unstudded felt soles fror my boat.
