Pololu Stackable 0.100″ Female Header with Extra 0.3″ Spacer: 2x20-Pin, Straight

This extra-tall stackable 40-pin female header features two rows of 20 pins spaced with a 0.1″ (2.54 mm) pitch. It includes three 0.1″-thick spacers for additional clearance, and the extended pins allow multiple units to be stacked as popularized on Arduino shields. The 2×20 size is notably used on the Raspberry Pi Models A+ and B+, and the extra 0.3″ of height allows for stacked boards to clear all of the components on the Raspberry Pi B+.