EOTech / Bushnell Model 500 Holosight

The initial Model 500 series of EOTech sights was introduced in approximately 1999, replacing the 400 series. This new model changed the form factor of the sight to what we still see today, with a fully enclosed system and internal zeroing adjustments (and without the 400’s interchangeable reticles). The first models were the 502, using a pair of N-cell 1.5V batteries. Where the 400s had been largely used on open-class competition pistols, the 500 began to see more use on long guns, and was eventually picked up by a variety of military forces, leading later to the 510 and 550 families. These optics were still marketed through Bushnell, and called “HOLOsight”.