The Pentax HD D-FA 28-105mm f/3.5-5.6 ED DC WR Lens is a versatile standard zoom lens designed for Pentax full-frame DSLR cameras.
 Here's a breakdown of its key features:  

Focal Length Range:

    28mm (wide-angle) to 105mm (medium telephoto)   

This range covers a wide variety of shooting scenarios, from landscapes and architecture to portraits and everyday snapshots.  

Aperture:

    f/3.5-5.6 variable aperture   

    While not exceptionally fast, this aperture range offers a good balance of image quality and size/weight.

Optical Design:

    HD (High Definition) coating for reduced flare and ghosting   

ED (Extra-low Dispersion) glass elements to minimize chromatic aberrations  
Aspherical elements to correct distortion and improve image sharpness  

Weather Sealing:

    WR (Weather Resistant) design with seals to protect against dust and moisture   

Focus System:

    DC (Direct Current) motor for fast and quiet autofocus   

Build and Size:

    Compact and lightweight design for easy portability   

    Durable construction for reliable performance