The first generation was the SMC Pentax-DA 55-300mm F4-5.8 ED, green side band.

That lens design was additionally released with a plastic mount plate as the SMC Pentax-DA L 55-300mm F4-5.8 ED with a silver side band.

This upgraded the lens to HD coating, offering improved transmittance and reduced aberrations.

The 55-300mm lens was finally completely overhauled in 2016 and made about a third of a stop slower throughout the zoom range, and even more so at the long end.

This version has a built-in Pulse Motor (PLM) for quieter, faster and more accurate autofocus, and a retractable design for easier transport.