The PCMCIA is a universal expansion slot which was originally for memory cards however over the years has become more popular for 56k modems, Wireless, LAN, and even USB cards.

PCMCIA Cards come in three types: Type I/II/III. These types refer to the thickness of card; Type I - 3.3mm, Type II - 5.0mm and Type III - 10.5mm. Because they differ only in thickness, a thinner card can be used in a thicker slot.

You can expect the refurbished laptop you buy to have Type II version as it is the most popular slot thickness. In fact Type III cards that would demand a thicker slot, are becoming far less commonplace.