in general, there are two ways to put some sponge on your strings and deaden them. you have the old fender way, foam over the strings, used by anyone who didn’t take off their ashtray bridge cover in the 60s and 70s. and you have the more widely used “diy” sort of way, under the strings, which is usually done by those who don’t have ashtray covers on their bass, and don’t want to tape stuff on top of their bass either. in my experience, over the strings sounds better to me. i have ashtray covers on my jazz bass, and the foam is harder to tame and have mute evenly when it’s under the strings, and it sounds worse when i play finger style that way. james jameson and carol kay and all those old school people also used their ashtray cover mutes.