Dubox™ & Bergstik™ Connectors Amphenol FCI's Dubox™ & Bergstik™ mezzanine connector system is a pin-in-socket board-to-board fully modular system on a 2.54mm pitch. Available in through-hole or surface-mount , FCI's Dubox™ & Bergstik™ connectors offer single and double row covering 2 up to 72 positions with a minimum stack height of 9.54mm. Double body headers allow for complete variable stack heights up to 26mm.