Patent ID: 7147343

Claim:
A flashlight comprising: a first housing section; a second housing section attached to the first housing section with screw threads; a seal between the first and second housing sections; a stop engageable against a surface on the first housing section to prevent the first housing section from separating from the second housing section by rotation of the first housing section relative to the second housing section; a single LED supported on the second housing section; a lens having a convex front surface, with the lens axially aligned with the LED and supported directly or indirectly on the first housing section adjacent to the LED, and with the lens and the first housing section longitudinally moveable relative to the LED, to a position where the spacing S between the LED and the lens is less than the maximum thickness of the lens, to focus light from the LED; and the LED having a directivity half angle A, and the lens having a focal length f, and with the ratio of A/f between 3.5 degrees/mm and 6.5 degrees/mm.