LM1815 chip.
Genboard v3.2 includes one LM1815 onboard, which is an input-shaping circuit used for variable-reluctance (VR) or coil type input trigger, when histeresys-comparator is preferred. Not needed for HALL-type trigger. Buy this if you need 2 channels of LM1815 circuit, or a spare chip . The few surrounding components (Rs and Cs) are onboard GenBoardv3.2 (and extra components in the rescue kit).