RS 2.54mm Pitch Unshrouded PCB Pin Header Connectors with Square Pins. Our own range of RS Pro PCB headers are unshrouded headers with 0.635mm square pins. They feature a 2.54mm pitch and are made from UL94V-0 black glass filled PBT. The contacts are plated with a pure and bright tin. Our RS Pro PCB headers are a through-hole solder termination for easy and permanent use. PCB Headers are used to connect two PCB boards together. This makes it highly efficient by not having to solder the board together or wire them and will save you time. It also makes it very easy to remove the second board if anything fails.. Features and Benefits:.