Mechanical pencils with 0.7mm leads are handy in the home, shop or office.
There is nothing magical about these particular pencils; they are just good value. They have a soft rubber barrel cover for a comfortable grip, a decent-sized eraser, and a push-button lead advance.
The best part is that you should still have a few left from your dozen after family members have each borrowed one "for just a minute".
Use standard-size lead refills.