I've had a pair of these Tobeco dna 30's for a few weeks now and for the moderate dripper they work out great, I like them much better than my Segelei 30. They have three buttons and stay at the power you set it to. I run dual 1.5 ohm coildripper so about 0.7 ohms around 20 watts on the drippers. I recommend these as a good buy, much better than the cumbersome battery draining Segelei.