Square D (Schneider Electric) ZB5AVG6 HarmonyLight Block Assembly. Schneider Electric Harmony™ Square D™ Light Block Assembly, Series: ZB5, 22 mm Size, Integral LED Lamp, 110 to 120 VAC, Screw Clamp Terminal, Plastic, Blue, 1.65 in H x 1.18 in W x 1.26 in D Dimensions. Additional Description: SQD -ZB5AVG6 MOUNTING BASE W 120V BLUE PROTECTED LED. Catalog Description: Harmony XB5, Light block with body/fixing collar, plastic, blue, integral LED, 110 120 V AC.