For best results use in a dimly lit room against a dark background. This hand held portable model requires 4 AA batteries Short wave Lamp This Short wave lamp will clearly show you the phosphor and the phosphor afterglow on GB stamps up to 1992. For best results use a short wave lamp in a dark room, the darker the room the better. To see the different coloured phosphors on the 1960 Wildings issue its the phosphor afterglow you are looking for when you turn the UV light off, Green phosphor is the brightest (10 seconds afterglow) followed by blue, (15 seconds) the Violet has a very short afterglow (5 seconds) It will be difficult to see the after glow in daylight, the darker the room the better. This two hand held portable model requires 4 AA batteries (Not included) Package Includes: 1 x 254nm shortwave UV lamp Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.