From the manufacturer:
Sleek, Fixed Sleeve Design for Technical and Everyday Use! The Sakura XS Series of mechanical pencils features a fixed sleeve that protects the pencil lead when used with rulers or templates. The pencil comes in 0.5mm, 0.7mm and 0.9mm widths for thin to bold lines and maximum versatility when writing or drawing.
The refillable eraser is easily accessible under a metal cap.