The most expensive sex dolls (approximately $1,200 and up) are usually made from silicone (usually above $3,000 at 2016 prices) or thermoplastic elastomer known as TPE (below $3,000). Dolls made of either material can be very lifelike, with faces and bodies modeled on real people in some instances, with realistic skin material (similar to that used for movie special effects), and with realistic (or even real) hair. These dolls usually have an articulated PVC or metal skeleton with flexible joints that allow them to be positioned in a variety of positions for display and for sexual acts. Silicone or TPE dolls are much heavier than vinyl or latex inflatable ones (which consist mostly of air), but are roughly half the weight of a real human being of comparable size.