Dippin' Daisy's Swimwear Green Halter Bikini Top - it's a size Medium and in good pre-owned condition (small pen mark on the left side halter sash). Possibly vintage. No idea what bra cup this would fit.

Halter neck sash straps
String ties
Padded (not removable)
Shell: 80% Nylon, 20% Spandex
Lining: 100% Polyester

#147

Dippin Daisy Daisys