When Victoria's Secret came out with their version of the G-string they renamed it the V string to lose the "trashy" or other sterotypical names that followed the G string around.
Later to be followed by the introduction of the T string
A "Vee-String Vagina Prosthesis" is an undergarment in the basic shape of a G-string which has the appearance of an artificial vagina colour-matched to the wearer's skin. Aimed primarily at crossdressers and at a male-to-female transgender niche market, it exists in various models - some of which claim to allow urination, masturbation or sexual activity with the vee-string in place. Evidently, your mileage may vary.
Confusingly, there have been multiple attempts to trademark "v-string" or "vee-string" (which are phonetically identical) for different products. Victoria's Secret has been trying since 1998 to trademark "v-string" as a store-branded variant of what is basically a g-string. Castle Supply has been trying since 2002 to trademark "vee-string" for an artificial prosthetic vagina, worn much like a g-string but for M2F TG's. And then there's the "v-strings that win" logo and slogan which had been used by Victory Sports for strings for tennis or badminton-style rackets apparently since the 1950's.
You might come out of this feeling like a new woman, or you might come out feeling that this is just another underhanded racket. Caveat emptor.