This is an officially licensed David Hasselhoff product.
Shirt features David Hasselhoff with sunglasses and one of those floaty things they use in Baywatch and says "Hasselhoff saved my life".
Sheer t-shirts are made of a soft material and are slimmer fitting than your average t-shirt. Sheer t-shirts are generally made of a cotton/polyester blend, but may also be 100% cotton. The shirts are not see-through nor is there any loss of quality.