I bought this meter as an extra meter for experimental testing of system designs involving stove leakage, heater off gassing and I have to say I like the rapid data updates, great sensitivity and alarms! I'd take this caving or use it for a work place, good battery life. It's a great deal for this kind of device. I like the case and the belt clip. Minuses, by the look of it it would probably short out if you fell in any water. Also the alarm voice has a weird thick Chinese accent and I haven't used it for a full year yet. But I'm not looking at this as a 10 year investment and the data accuracy seems pretty solid. So overall I'd say it's a great deal for the money. 5 stars.The product works as long as you're at sea level. Problem is most mines are at higher altitudes where the oxygen has a lower concentration naturally - so the alarm is constantly going off. Without being able to compensate for this, the product is useless. Contacted the manufacturer in India but no response. It came without a manual and none are available online.UPDATE: The company contacted me and provided a manual (which was missing from the original packaging) You can indeed change the thresholds, which we did to 19%I have worked with meters in hazardous materials response for 25 years and have used many name brand, high dollar, meters. So far, this one ranks as one of the best because of the price. Meters similar to this go for 4X the cost of this one. It was very easy to navigate the menu and change the alarm parameters. The meter calibrated easily, with gas I had lying around. The meter does take a few minutes to warm up. You can tell when it is ready, when the oxygen sensor settles down. I don't believe that the meter is intrinsically safe for flammable atmospheres, so you have to watch the LEL sensor closely. I plan on using it for training, but I would trust it down range.Very Loud battery alarm and short battery lifeThis works well. Reading the same as our 700$ MSA unit. We returned the msa and got 4 more of these.Save your money and buy this over the MSA.Ordered this monitor. Thought it would be a cheaper alternative to buying new sensors for a MSA solaris ($80/pc). Turned it on and it reads 19% o2 in my kitchen. Go outside and no change. I know this is impossible so I compared with a MSA solaris at work (underground mine). Solaris reads 21%. This one 19.1%. Obviously out of calibration. Returned for a replacement. Replacement comes I turn it on in open air outside and it reads 20%. 2 for 2 out of calibration. Will be returning. Dont waste your time with this monitor, you WILL DIE if using it for what gas monitors are for. I only wish I would have bump tested the other 3 sensors at work with calibration gas. If the o2 is out of calibration I wonder if the other sensors are even functional.Ease of use and convenient.Gas station sump entry.Buena presentación desde el estuche donde viene el detector, el equipo se percibe de buenos materiales y las lecturas son bastante precisas.Llegó un poco antes y en perfectas condiciones