Hirose A1 and A2 Series 2.54 mm PCB Pin Header Connectors. A1 and A2 series 2.54 mm PCB pin header connectors with a high density PCB space saving design. These A1 and A2 series PCB pin headers are available in a single row configuration (A2 series) or double row configuration (A1 series). Straight and right angle options are also available. These A1 and A2 series PCB pin headers mate with the A1 and A2 series 2.54 mm crimp connector housings.