Surfers also wear wetsuits in colder regions. David and another man (Rossi) enter the canals wearing wetsuits and scuba gear. Neoprene was not the only material used in early wetsuits, particularly in Europe. Wetsuits provide both thermal insulation and flotation. Other developments in single-backed wetsuits include the suits designed for free-diving and spearfishing. Sharkskin is commonly used as a liner in diving suits and wetsuits. The colorful wetsuits seen today first arrived in the 1970s when double-backed neoprene was developed. Protection from heat loss in cold water is usually provided by wetsuits or dry suits. Gatherers are not allowed to wear wetsuits or even put their heads underwater. Various types of wetsuits of varying thicknesses are used in open water swimming. Buoyancy changes associated with wetsuits were found to be a significant factor. From those wetsuits, Body Glove branched out into other product categories. He used that logo on all his boards and wetsuits for most of his career. These weights are often marketed as being less abrasive to wetsuits. The plastic coated weights may be marketed as being less abrasive to wetsuits.