Btec Medium Downlighter - Ø167mm, IP40 Recessed downlighter with spun aluminium housing, spring steel retaining clips and high transmission polycarbonate diffuser. Options: LE3 - Lithium Emergency (476 lumen output) LS3 - Lithium Selftest LA3 - Lithium Autotest CB - Please specify 50v, 110v or 230v when ordering S - Switch Dimming D - Digital Dimming (DSI) A - Digital Addressable Lighting Interface (DALI) C - Bi-Level Dimming (Corridor Function)