Shepherd's whistle
They are also produced commercially. Simple whistles may cost less than 1 USD in bulk; expensive ones may be quite ornate. They are commonly made of plastic, aluminum, stainless steel, silver, brass, titanium, Corian, jade, buffalo horn and other materials.
Ron Foxcroft
Foxcroft often became frustrated with the traditional design of referees' whistles, which features a "pea" (cork ball) inside that is prone to jamming, thereby preventing the whistle from producing sound. He was inspired to create a "pealess" whistle following incidents in international games including the 1976 Summer Olympics in Montreal and the 1984 pre-Olympics game in São Paulo, in which Foxcroft witnessed an obvious foul but he could not stop play as his whistle was rendered useless by a jammed pea; play continued and the referees were booed by spectators. Foxcroft collaborated with an Ontario design consultant, Chuck Shepherd, to design a pealess whistle; they established Fox 40 International in 1987, and the company's whistles were first used at the 1987 Pan American Games in Indianapolis. Throughout the 1990s, Fox 40 whistles became the standard whistle for referees and officials in numerous major professional sports leagues including the NFL, CFL, NHL, NCAA and NBA; it has also been adopted as a standard by numerous public safety agencies around the world. Today, Fox 40 International dominates the whistle industry with thousands of whistles produced each day in Canada.