"CEU IS THE ELECTRICAL INTERFACE BETWEEN UPTO 16 SMOKE DECTORS IN A CARGO AREA AND RELATED EQUIPMENT IN THE COCKPIT,SUPPLIES: POWER , GROUND , BUILT IN TEST INPUT , MONITORS SMOKE DECTORS FOR ALARM SIGNALS,SIZE: 7.14 INCH LONG BY 6.40 INCH WIDE BY 2.50 INCH HIGH, VOLTAGE INPUT +18 TO +32 VDC , STANDBY POWER:100MA MAX , CEU CONTAINS A CIRCUIT CARD , 2 CONNECTORS P1 AND P2 , 2 CONNECTORS J3 AND J4, LEDS , PRESS TO TEST SWITCH , AND LAMP TEST"