Unlike the tube naming convention, if there are two transistors in a single envelope, the type letter was never repeated - so a dual NPN RF transistor might get a type "BFM505" rather than something like "BFF505" for instance.
I den nye konvention anvendes ikke to ens bogstaver f.eks. for to transistorer i samme hus, som man gjorde ved rørkonventionerne – så en dobbel NPN HF transistor kan få benævnelsen "BFM505" i stedet for noget lignende "BFF505".