Review on Universal Black A/C Valve Core Remover/Installer by MASTERCOOL - Model 58490 by Tom Reid

Most of the bad reviews here are obviously user error. This tool is not really intended for the average handyman. When you're working on a printing system, it needs to be treated like a bomb, because that's what it is. Most modern heating, ventilation and air conditioning systems are under high pressure and compressed gas in a closed system is in most cases a bomb. That being said, if you use this tool carefully and thoughtfully, it works well. It's very well done. However, on some accessories, some O-rings were not fully installed. A quick jab with the pickaxe fixed it. Overall I recommend this tool if you are a pro. This is the most versatile kit I have come across as it also works with the R-22 and R-410a home systems.