When the last of my digital tire pressure gauges, which are no longer manufactured, recently stopped functioning, I began research to find suitable replacements. There are of course many digital tire pressure gauges from which to choose, however the vast majority of them failed to impress for a variety of reasons, not the least of which were their poor or mediocre specifications or numerous user complaints. After a considerable amount of research, I located the Etenwolf T300 digital tire pressure gauges on Amazon. The most significant data which received my attention is that the Etenwolf T300 gauges conform to ANSI/ASME Standard 40.7 2A. I had not previously encountered affordable, consumer grade gauges that were calibrated with that level of accuracy. ANSI Standard B40.7 level 2A is a standard which applies to digital process gauges, and specifies accuracy within a +/- 0.5% span of permissible error. That level of accuracy means that on a 35psi automobile tire, the expected accuracy of the gauge is within +/- 0.175psi which is a ridiculously high level of accuracy for inflating a typical automobile tire. However, that ANSI B40.7 2A claim appears to be an error on the webpage. According to the printed manual which accompanies the T300, and according to the individual Calibration Certificate included with the gauge, the T300 actually conforms to the far more stringent and more precise B40.7 Level 3A standard. B40.7 3A specifies accuracy within a span of +/- 0.25%. That is a level of accuracy that is needed for industrial test gauges. The other specifications provided in the product description included the usable range of 3 – 200 psi which makes the Etenwolf T300 suitable for almost any tire I can reasonably expect to use, including my low-pressure garden tractor tires. Another factor that I found very appealing is that the Etenwolf T300 is powered by 2 – AAA batteries. Many tire pressure gauges require button batteries of various sizes, which never seem to be immediately available to me when they require replacement. With the ubiquitous AAA batteries, I am assured that I will always have replacement batteries readily available when needed, and even when away from home, they can always be easily purchased in almost any local store. Etenwolf provides 2 Duracell alkaline AAA batteries with the T300. I have also used the gauges with Ni-MH rechargeable cells, and they perform perfectly well. I ordered a Cyan case T300 because Amazon had them available for more rapid delivery than the Orange model (there is also a Gray model, which was out of stock when I purchased). Once I received the T300 and evaluated it, I was very impressed. The plastic case appears to be a reasonably thick, and potentially durable gauge of injected plastic. The T300 has a very solid feel and heft, which impressed me. The assembly of the T300 appears to be very good and precise. This tire gauge genuinely appears to be of very high quality. The battery compartment at the end of the unit has a slide-out which also stores an included Presta valve adaptor for high-pressure bicycle tires. The white 4 place LED display digits appear to be 11mm tall x 5mm wide. The gauge resolves to 10th PSI (1 place right of the decimal). Most tire pressure gauges only resolve to ½ PSI display. There is a momentary, rocker type switch on the lower part of the case which controls all functions including power and unit of measure selection. The T300 can measure and display PSI, kPa and bar. Holding the switch for 6 seconds will turn the power off, but the gauge will also shut down automatically after 30 seconds of non-use. After a measurement, the gauge resets to 0 in approximately 5-6 seconds for repeat measurements. The digital display also displays low battery level once battery reserve falls to 20% or below. The nose of the gauge, which must mate with the tires Schrader valve, seals very tightly against the tire valve. There appears to be a compressible rubber gasket in the nose fitting, which ensures a solid, leak-free union with the tire valve. Resultantly, the T300 produces very quick and reliable measurements without the need for repeated repositioning efforts to get an adequate seal for a reliable measurement. There is a white LED lamp below the nose piece which makes use in dim or dark environments possible. I evaluated the functioning of the gauge by taking multiple (many) repeat measurements using both PSI and kPa scales. The repetitive consistency and accuracy of the readings was notable. I was so favorably impressed with the T300 that I ordered a second gauge (this time with the orange case). When I received the second T300 I could not resist comparing them. I collected more than 20 successive measurements, alternating the gauges. (Total of 44 measurements collected). Half of the measurements were obtained in PSI and the other half in kPa. The consistency and accuracy both with the same gauge, and between the gauges was extremely impressive. I believe that the Etenwolf T300 tire pressure gauge is outstanding. It is well constructed, giving rise to the belief that it will be very durable. It is extraordinarily accurate, being calibrated to a measurement standard which applies to industrial process gauges. It functions very well and with consistency. The Etenwolf T300 is the best tire pressure gauge that I have used, and I am hopeful that it will provide many years of reliable service. I would not have purchased two of them if I was not extremely impressed with them!