Problem Meets Sonnet Solution. ExpressCard/34 to 54 Stabilizer Attached If your laptop computer has an ExpressCard/54 slot, using ExpressCard/34 adapter. I recently bought an eSATA Expresscard 34 adapter for my laptop (which has an expresscard 54 sized slot). I am concerned that when the. ExpressCard, initially called NEWCARD, is an interface to connect peripheral devices to a A diagonal guide in the rear of the 54 mm slot guides 34 mm cards to the connector. Adapters are available for connecting an ExpressCard/34 card to a CardBus (but not bit PC Card) slot via internal USB bus only (not.