• Pentax K Mount

• 53.5mm (35mm Equivalent)

• Aperture Range: f/2.8 to f/22

• Macro 1:1 Maximum Magnification Ratio

• 5.5" Minimum Focus Distance

• High-Grade Multi-Layer HD Coating

• Super Protect Lens Coating

• Quick-Shift Focus System

• Nine-Blade Diaphragm

You can find in here an in depth review of it