Pololu - 0.100" (2.54 mm) Breakaway Male Header: 1×40-Pin, Straight, Black
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80 Pieces Male and Female Pin Header Connector 40 Pin 2.54 mm Single Row Straight Pin Compatible with Arduino Shield: Amazon.com: Industrial & Scientific
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Pololu - 0.100" (2.54 mm) Breakaway Male Header: 1×40-Pin, Straight, Black