Illuminated Push Button Head, Spring Return, for use with BA9s Lamps, ZB4-B All heads require fixing collar/lamp holder/contact assembly typical stock no. 330-9760, plus a BA(s lamp of choice (neon, LED or incandescent to 2.4W max) Cannot be used with integral LED light blocks Schneider Electric ZB4-B & XB4-B Harmony® 22mm Range