Click to open the relevant instruction manual: (note - some items are no longer available, the instructions are included here to help existing customers). C401 timer C420 timer C450 timer C600 timer C601 timer C601R wire-free timer C700 timer C720 timer C800 series - quick guide C800 series - RS232 output C820 timer C830 timer C841 timer C846 timer D505 red led display D510 yellow flap display D510 digit replacement D510 pcb replacement DX display radio link K10 bell K11 bell K20 display test set K30 clock/marathon timer K531 K531-channel coding K531-delay