... 21w,28w,35w 4) high efficiency Features:1.Material:aluminum body with PC cover2.Adopt high quality ballast,comply with 3C,CE standard;can ... pass EMC and RoHs.3.High quality:PF>0.99 ... ,THD<10%,Usual quality:PF>0.95,THD<30%4.Use tri-phosphor powder fluorescent lamp,more brightness,high ...