The most popular style for heat exchangers, the double-jacket offers complete protection of the filler material. There is practically no diameter limitation, with greater compressibility and resilience than a similar solid metal gasket. This gasket provides even support by the use of the overlapped jacket on the inside and outside diameters. Also, the outside lap helps to prevent excessive distortion of lightweight flanges. The most common filler used is graphite. A wide range of metal and filler material is available if dictated by temperature, pressure, or corrosive conditions.