A cryptic pattern (white) displaying the hour (left column) and 5-minute interval (right column) is laser etched onto black plastic in order to produce the clock face. The pattern requires a "Decoder Key" (white with two pairs windows) in order to be deciphered, one column at a time, first hours (left column) and then minutes (right column). Since I want just one number pair to be visible at any given time the cryptic pattern was designed such that the left column numbers are vertically offset from the numbers in the right column. From top to bottom the left column displays the hours as 01, 02, 03 ...12 and the right column displays the 5-minute intervals as 00, 05, 10, 15, ...55. The Decoder Key's default position is at the top where neither hours nor minutes are being decoded. When the clock is activated by the button in front the Key first moves to reveal the correct hour and after a brief pause the Key returns to the top and then moves to the correct 5" minute interval.