Mersen FSPIN1 Accessory Pin Brand: Mersen. Part Number: FSPIN1. Mersen Accessory Pin, For Use With: Finger Safe Power Distribution Block, 0.1 in H x 0.35 in W x 2 in D. Additional Description: MERS-FSPIN1 FSPDB ACCESSORY PIN TO FORM MU. Catalog Description: FSPDB Series UL 1059 Finger-Safe Power Distribution Block..