The best pocket comb will not be the same for everyone, but important things to consider are comb size, type of teeth, desired material or flexibility, and price. For many people, a cheap comb or plastic comb will be adequate. These can be purchased in any drug or discount store. For others, slightly better quality types of combs will be necessary.
A pocket comb should, by definition, fit into your pocket. At the very least, it should be small enough to carry in a purse. This rules out most larger combs, although some longer plastic combs are narrow and flexible enough that they can protrude from your back pocket without discomfort. Another longer type of comb that can be carried in your pocket, often your back pocket, has a handle.
Pocket combs with a distinct handle are easy to grab from a back pocket, and part of the fashion of carrying this style of comb is the handle's visibility. Combs with a handle will usually have medium to widely spaced teeth for easy detangling or feathering, but they might not be ideal for very fine hair or close styling. A pocket comb with a handle can also be bulky.
Another popular variety is a small plastic comb that doesn't have a handle. These combs are thinner and less bulky to carry, and they often have two types of teeth spacing. One half of the comb has medium spaced teeth for tangles and thicker hair, while the half of the comb has finely spaced teeth for thinner hair or more precise styling. These combs are usually made of plastic or hard rubber, but because they're smaller than handled combs, they can break more easily, particularly the teeth. It's therefore helpful to look for the variety advertised as "unbreakable."
Yet another type of plastic comb is the retractable or switchblade model. These combs fold in half and open like a pocket knife, making them highly portable in your front pocket, although a little bulky for the back pocket. They usually have fine to medium spaced teeth, and it's useful to know that the teeth are very short in length because of the comb's design. This can make it hard for the teeth to grip your hair well when grooming.
Material will usually determine the price of a pocket comb. Although most are made of plastic, you can also find small portable combs made of horn and even precious metals. Natural horn combs can be expensive, and silver or gold combs can cost still more. If one is seeking a pocket comb made of special or particular materials, it helps to be specific when searching online.