The Mark 708 with Double Packing is an alternative to a bellows stem seal, and is used when standard packing will not adequately contain the controlled media. The optional bonnet features a double packing arrangement separated by a lantern ring. With a double packed bonnet, lubricant is pumped into the packing sets, supplying a tight seal similar to that provided by a bellows stem seal. The double packed bonnet is an excellent choice when service conditions could cause damage to a bellows assembly.