This stackable 40-pin female header features two rows of 20 pins spaced with a standard 0.1 (2.54 mm) pitch; this spacing is the same as on most solderless breadboards and matches 0.1 male header strips. The extended pins allow multiple units to be stacked as popularized on Arduino shields, enabling removable daughter boards that can access pins without blocking them. The 220 size is notably used on the Raspberry Pi Model A+ and Model B+ as well as the Raspberry Pi 2 Model B and Raspberry Pi 3 Model B, and its height matches our 11 mm M2.5 standoffs for Raspberry Pi.