The Seymour Duncan Vapor Trail is driven the infamous BBD chip, which was used in many classic delay pedals. BBD stands for Bucket Brigade Device - which, electronically, you can liken to a queue of firefighters passing buckets of water. Each stage of a BBD chip employs a single capacitor. Like those afore mentioned water buckets, an audio signal is passed from one capacitor to the next within the BBD chip - once per clock step. Slow down the clock and you get a longer delay; speed it up and you get a shorter one. The result is a vintage-sounding delay with its own inimitable sonic signature.