This Swiss mechanical pencil (introduced to the world in 1929) was the first to use a push-button lead release.
What makes this model still a winner 80+ years later is the light, rugged, machined aluminum body and a specially toughened lead that can be used on rough lumber without breaking or slipping in the four-jaw collet chuck. The leads are 3mm in diameter, but the sharpener in the push-button cap can put a point on one as fine as you get on a 0.5mm lead. Even with a fine point, the lead stands up to tough use.
These mechanical pencils are for craftsmen, not office workers. This is one you can carry in your back pocket and never worry about breaking it just because you sit on it. It is equally durable marking rough or planed lumber all day long without breaking a lead.
The 5-1/4" long pencil comes with one HB-grade lead. Additional leads are available in a package of 6. (Color of push-button cap may vary.)