Harvard Engineering PLC high frequency fluorescent light ballast. 

Part number DKE28, 28w GE-2D, PL-Q.  Input 220-240v, input frequency DC 50/60Hz, input current 0.13 (max), power factor 0.98, Ta -10C to 50C, Tc 75C.  Made in UK.  Fits various makes and models of 28w 2D light fittings.

New condition.  Please check that this is the correct type for your model of light fitting before purchase, as returns are not accepted.