Smiley 1/2 Wave Telescoping Antennas
Half wave antennas are meant to be used for situations where you do not have a good ground plane (such as on snow or water, or standing on the deck of a fibreglass boat). These antennas are only available with BNC and SMA-M base types on them. They are superior to the 5/8 telescoping when you are on high ground, or do not have a ground plane when in valley bottom terrain.
Although they are listed as '2 Meter', they can be tuned through the full VHF spectrum as seen on the below chart (click to view larger version in new window).