In reading other reviews, it looks like the makers of this product have changed the design.  I'm a 34B and it fit my chest perfectly on the smallest adjustment without puckering or needing to be pinned.  It can be adjusted to two wider widths.  It would work with any size bra strap.  The product's straps wrap around your bra stap and then snaps with about at least an inch of room for your strap.  I needed it to use with a dress for church and it stayed in place all day, while wrangling a two-year old.  It's made out of slip material and looks like a camisole that you'd wear under sheer clothing. I'd give it 5 starts if it had more of a clothing look and less of an under garment look, but it saved the day for me and I do recommend it.