It is essentially an electronic cigarette that uses an oil cartridge. In this instance the cartridge is filled with hash oil. I have since found that the "Rempen" is actually made by eGo-T and can be purchased online for around $25 for two! Low price! Here is a picture of the "pen."
The pen unscrews and you can screw a charger into one part of it to charge the battery. My unit came with a charger with a USB end and a wall plug with a female USB plug. I had a cigarette lighter USB plug so I can charge the unit anywhere.
To use the unit you place a plastic cartridge with the oil into one end. This becomes the mouth piece. To smoke you simply push a small button on the unit while you inhale.
IMHO - this is the best portable vaporizer I have used. I have an MFLB and love it, but this "pen" is much easier to use and much cheaper. Some of my friends who do not like the MFLB at all really liked this pen. There is no need to fool with a separate battery and a stem like with the MFLB, although the pen has three parts they all assemble together to make one unit.
Although I find the pen easier to use and much more like smoking a joint, the pen will not replace my MFLB entirely. The pen does have a few drawbacks that the MFLB does not have.
First, the pen uses cartridges that must be purchased from a dispensary. Now, you can buy refillable cartridges for these pens, but I am not sure if you can use straight hash oil in the carts. The package my cartridge came in says it contains "Sirlene, and Hash Concentrate. The MFLB, of course, uses finely ground weed - so you can grow your own if needed. So the MFLB is better for many in that respect.
Second, is cost. I have just purchased my pen and I am on my first cartridge so I don't know how long the cartridges last. The dispensary sells the cartridges for $30. So far the cartridge has lasted through an evening of three heavy smokers hitting it all night, and it is still going. So, it looks good but I will see if it is more or less expensive than just buying weed.
So in summary - the Rempen or eGo-T pen is an inexpensive and stealthy way to ingest THC. It is easier to use that the MFLB, however is limited to using prepared cartridges and can not be used to smoke regular weed.