Are you confused by the many different electric essential oil diffusers there are to purchase? Any search for aromatherapy diffusers at some online retail website like Amazon reveals hundreds of products to choose from. How do you know which one to purchase? There are a few things you should look for to make sure you are getting a quality product.Check out Coverage AreaMost essential oil diffusers require anywhere from 3 to 5 drops of oil mixed into the product's water tank. The aroma is then diffused into the air. So you need to know how effective a product is in delivering coverage to the room you are going to be occupying. Two very similar aromatherapy diffusers may differ in coverage area by as much as 100 square feet or more.Understand How Long a Diffuser LastsA recent search on Amazon for essential oil diffusers returned 2 nearly identical products. They were virtually the same price, both covered the same area, and they even looked alike. However, one product lasted 10 hours on 3 to 5 drops of your favorite essential oil, while its competitor only lasted 6 hours. Knowing how long a single application of essential oil will last is important when making a buying decision.Personal Preference Is Important TooTo put it rather plainly, some aromatherapy diffusers are downright unattractive. They work great, but you will want to hide them somewhere in your home. On the other hand, products like the BellaSentials Essential Oil Diffuser Premium run a full 12 hours and are priced the same as similar models. This product is designed in a bamboo covered disk shape which is visually pleasing. Once you understand how long a diffuser will last and what its coverage area is, visual appeal might be the deciding factor when you make a purchase.