A weed pen is a device that vaporizes cannabis extracts for inhalation. The pen typically has a mouthpiece, battery and chamber. It differs from other vaping accessories like e-cigs that use liquids or oils. Dab pens (also called dabs) are the size of a highlighter and designed for use with solid and semi-solid cannabis concentrates that come in several forms, from thick liquid to glassy, hardened compounds known as dabs.Source :weedsmart.cc

Compared to smoking flower in a joint or blunt, using a weed pen is a more discreet and efficient way to get high. Vapor pens produce less smoke and leave behind no lingering scent, and they can deliver high-quality flavor by letting terpenes and other chemicals in the extract shine.

There are many different weed pens on the market, but they generally fall into one of two categories: vaporizers and dab pens. Most vaporizers are compatible with multiple types of extracts and can be adjusted to accommodate different strengths of hit, but dab pens are specifically designed for specific types of dabs and are not interchangeable.

The heart of a weed pen is its atomizer, a small heating element that transforms cannabis oil or dry herb into vapor. A battery powers the atomizer, with its capacity influencing how long the device can operate before needing a recharge. Some pens have removable batteries and are reusable, while others require disposable cartridges that need to be replaced regularly.