Description by Pentax:

The Pentax DA 40mm f/2.8 XS Lens is specifically designed for the APS-C sized Pentax K-01 mirrorless camera. The 40mm focal length is equivalent to 61mm on a 35mm format, and provides a slightly longer angle of view than normal. 

•  9 rounded aperture blades provide a smooth, natural quality to the out of focus regions of the image; especially in highlights. 
•  Minimum focusing distance of 15.72" / 39.93cm for close up work. 
•  Designed by Marc Newson for a minimal and attractive profile. 
•  Pancake-style design is unobtrusive and lightweight, measuring 0.36" / 9.1mm thick and weighing 1.8oz / 51g. 
•  SP (Super Protect) coating helps front lens element repel moisture, dirt, and dust while providing greater contrast and color to your images.