Bright Uv Blacklight Invisible Ink Spy Pen Ultraviolet PLUS FREE BONUS Most durable even for children no felt tops to break off and yes even attractive enough for the executive! This 2 in 1 pen has a UV tip for writing and the super bright ultraviolet bulb for reading your invisible message! This pen will write on all surfaces including glass and skin! Super light weight the lightest one on the market today! just 3 tenths of an ounce! Each pen is individually wrapped and includes 4 AG3 batteries (button batteries)