Hopes this helps! The strap is made of great quality ( Gold Hardware ) not plastic. It is one size fits most, as it adjusts like a normal bra strap. If for some reason you need a custom size, I will accommodate the best I can. Very simple and easy to wear.
I recommend wearing this if you are wearing very tight clothing. It will keep the bra snug to your body. Or when you have an active day or night planned; dancing, jumping, sweating etc... This strap is optional, though provided for your comfort.