QUOTE=uberingram]How is this different from the unit Forge offers? Just curious.[/quote]
Forge uses a diaphragm, Samco uses a piston
Pic from box - includes words and pretty pictures. Samco makes both piston type and diaphragm, depending on application:
http://img67.imageshack.us/img67/1523/samcoboxsc6.jpg
Note: SRT-4 is a single-piston BOV, not the depicted dual piston shown on the box, but the basic design difference can be seen...