For best results, use in a dimly lit room against a dark background. This handheld portable model requires 4 AA batteries.<br> Short wave lamp.<br> This short wave lamp will clearly show the phosphor and phosphor afterglow on GB stamps up to 1992.<br> For best results, use a short wave lamp in a dark room; the darker the room, the better.<br> To see the different colored phosphors on the 1960 Wildings issue, observe the phosphor afterglow when the UV light is turned off.<br> Green phosphor has the brightest afterglow (10 seconds), followed by blue (15 seconds), while violet has a very short afterglow (5 seconds).<br> The afterglow may be difficult to see in daylight; a darker room provides better visibility.<br> This handheld portable model requires 4 AA batteries (not included).<br> Package includes:<br> 1 x 254nm shortwave UV lamp