What size is an ExpressCard module?
There are two sizes of ExpressCard module: one is 34 mm wide (ExpressCard/34) and the other is 54 mm wide (ExpressCard/54). Both modules are 75 mm long and 5 mm high. Host systems can provide either a Universal (54 mm) slot or a 34 mm slot. A Universal slot, as the name implies, will accept either an ExpressCard/54 module or an ExpressCard/34 module. An ExpressCard/34 slot will only accept an ExpressCard/34 module unless an extender is used which would put the ExpressCard/54 module outside of the host system.
