Effetre glass (pronounced as /it/, Italian F3, abbreviated form of fratelli tre, "three brothers"), once known as Moretti glass, is a kind of glass used in lampworking. It is considered a medium-soft glass and is popular because of its wide range of colors and the ease with which it is molded and shaped when hot.[1] Genuine Effetre glass is made in Italy by the Effetre Murano S.r.l, on the island of Murano. It has a working temperature of 1733F and a coefficient of expansion value of 104.[2] [3] Effetre is a variety of soda-lime glass.