There are some characteristics to consider while you buying a breath alcohol tester. At first, decide on what type of breath alcohol tester you need. You must think about whether or not your device will be for your own personal use or if you are planning to test other people as well. One of the most popular sizes is the mini size since it is able to fit in any key chain. However, it is less durable. If you won't be the only person using the device, then you may need a slightly larger handheld model that accommodates for disposable mouthpieces. Some devices don't even require physical contact with the collection point to get a good reading, but be careful about the accuracy of these models.
At the same time, there are some types of breath alcohol tester available for you including semi-conductor or fuel cell. Fuel cell comes at more expensive price but it is able to provide you a more reliable choice. Consider the more accurate "fuel-cell" based breathalyzers versus the older semi-conductor based models. On the other hand, a semi-conductors type comes at cheaper price but it provides less accurate reading. This second type is mostly used by the customers. Then, which kind of system do you need, an actual numerical reading or just as simple red-light, yellow-light, green-light system? The second one will to tell you when your blood alcohol content is at a safe level to drive. Both will give good readings with proper use, but the semi-conductor based breathalyzers are more prone to giving false-positive readings - telling you that you're good to drive when in actuality you may not be.
Considering all those benefits you can get, it will be worth with the money you spend for it. It will be very beneficial for you to choose the clear digital read out.