kr808 (mf style) drippers, 2.4 to 2.8 ohm. These cartos are horizontal and work great and of course he has the lowest shipping around I could find. These cartos will work great on your 3.7 device and I use them on my buzzpro at about 4volts and still work great. great vapor, throat hit, have filled over ten times and still work like when I first got em, and they taste a lil off when it gets dry, telling you you need to fill again, but they wont burn and wont get messed up. Gotta have that horizontal. Would def get these if your looking for a carto and are new. Trying his new clear ones this weekend, another person wrote about in a post here, and they seem great, so I will compare these two, when I get em in. 
