CF adapters are meant to utilize SD cards in devices requiring the CF form-factor. These will be tempting to users upgrading from devices that utilized SD cards (because you spent a lot of money on fast SD cards and you want to keep using them). Unfortunately most CF adapters create a bottleneck. The bus speed of the adapter is nowhere near as fast as the SD cards themselves, thus they prohibit the device from reading/writing as fast as necessary. Note also that there are Type I and Type II adapters, just like with CF cards (type I and type II). This corresponds only to size. Type I is 3.3mm thick, while Type II cards are 5mm thick.