Tired of paying two bucks at the gas station, I have always yearned for a portable tire inflator. Here are two of the most popular models compared (Please see photo). Which is fastest, best built and most reliable?AVID TIRE INFLATOR OVERVIEW:Both of these cordless inflators resemble drills with similar lithium-ion batteries. The Avid has a 20 volt battery as opposed to the 12 for the Autder. Is this a real world advantage? More voltage means how much power the battery generates. Thus, the Avid is a bit more powerful and fills the tire a bit faster. Avid states that you can inflate three to four tires fully depending on tire size. For 214/60 R16, as an example, you can fully inflate three tires from flat and each tire would take about five minutes.For just topping off a low tire, the Avid works easily and relatively fast. Its maximum pressure is 100 PSI. I increased my car’s tire pressure from 32 to 41 in about 90 seconds.For accessories, you get a car adapter, a couple of inflation adapters, and a handy storage bag. You can buy an inexpensive second battery from Avid.AUTDER TIRE INFLATOR OVERVIEW:The Autder looks like my Dewalt drill but, alas, the batteries do not swap. The 2600mAh battery will last a long time. The mAh number determines how long a battery will hold a charge. This one should last a year in your trunk if not left out in extreme weather. As long as you are just topping off your tire pressure, the battery will last through many charges. If starting from a completely flat tire, the size of the tire with affect how much air you’ll get before running out. Figure on two tires if both are totally flat. In real world use, this is not a likely scenario, though. Maximum pressure is 120 PSI.For accessories, you get a great car adapter, a generous supply of inflation adapters, and an excellent storage bag. Audter does not sell extra batteries so you are limited to one.EASE OF USE: AVID VS. AUTDER:Both are equally adept at quickly topping off a tire, easy to use and were within 1 PSI of my trusty gauge. I found the Autder more intuitive and convenient to work with although both are quite usable. The Autder shows both the current pressure and desired pressure at the same time. Strictly used as a gauge, it’s easy to read, too. The available battery capacity left is also easy to access in the same area as the other readouts. The Avid can be toggled between set and desired pressures. The Autder is slightly quieter.WHICH HAS THE BEST WARRANTY AND SERVICE:Avid’s warranty is listed on Amazon as two years. Inside the box is a warranty card. Both companies respond promptly to questions.Here’s what Autder says about their warranty: “We promise you with one-year warranty, actually, we are not permitted to list the warranty on the listing according to amazon's rules.” That’s unusual. No warranty info is included in the box.RECOMMONDATIONS: WHICH IS BEST?Both air compressors are reasonably well built, similarly priced and get the job done confidently. Both have a convenient auto stop function when desired pressure is reached. At the time of this review, the Avid was about 15% less expensive. Consider this when deciding: The Avid will fill faster yet the battery won’t hold a charge as long in storage. The Autder will last a longer time in the trunk but at 12V vs. 20V for Avid, it won’t inflate quite as fast. You can buy a second battery only for the Avid.Both inflators rate 5 stars for ease of use. For warranty, the Avid rates 5 stars for a generous two years. With no option for replacement batteries, and a stated one-year warranty they say they are not permitted to list on Amazon, Autder’s service after the sale is not as confidence-inducing.