This accessory is used on pendants and sconces that don't already have a bottom diffuser. In the case of a pendant, the diffuser attaches via clip to the bulb. In the case of a sconce, the fixture is modified to hold the diffuser. Please specify which fixture this is being attached to when ordering.This accessory is used on pendants and sconces that don't already have a bottom diffuser. In the case of a pendant, the diffuser attaches via clip to the bulb. In the case of a sconce, the fixture is modified to hold the diffuser. Please specify which fixture this is being attached to when ordering