There are many butane hash oils.. One of them being Live Resin.
This type of extract starts off a little differently than most concentrates. Fresh (not dried) cannabis is the base product. The freshly cut cannabis will then be frozen. The exact temperature and length to not exceed is documented differently in each facility, however -10 °F and using the flower between 23 - 36 hours in the freezer has been recommended. Extracting live resin involves using below zero temperatures, liquid butane, and a very nice piece of technology. Precision explains is perfectly in this video!
The butane is frozen to below -30 °F, this requires very serious equipment.
The most common form of machinery is called a closed loop system. This closed loop system will take the frozen liquid butane, absorb it in the cannabis, the butane will attach all of the plants cannabinoids to it, butane (with cannabis infused) will be recycled back into a different freezer which will then liquify it. The solvent butane lifts the terpenes and cannabinoids off of the plant material and leaves it floating in the liquid butane. Once the liquid butane is forced through the material cannaster, it is then burned; almost like cooking off the wine in your famous marinate. When liquid butane has heat placed on it, it will evaporate and become a gas again. The closed loop system filters the gas and puts it back into the freezer so the butane can become a liquid. What is left over from that heating process is the new cannabis oil, called Live Resin.
This extract tends to have a better taste and transparency, depending on the quality of beginning material and extraction process. While it may not be the highest THC concentrate on the market, it is absolutely one of the greatest extract experiences you will have. There are two main reasons why people think this is. One being that it is fresh material, there is no drying or decarboxylating of the plant and two, using liquid butane and letting it be submerged in the plant material at the same cryogenic freezing temperature the butane was stored at prior to extraction.