Just started the cool dog electric voice coil iron earphone, and the Bluetooth connection of the earphone is very stable. I used it for five days without disconnecting. The product introduction page of the two units says that it is a high-precision moving iron unit and a moving coil unit, and imported composite titanium-plated diaphragm. Speaking of personal feelings, I usually listen to them at work every day. Relatively high rock music, with strong bass and very clear sound. I go to the gym to exercise after work. Because I'm IPX4 waterproof, I'm not afraid of sweat seeping into headphones. Before going to bed, I will listen to some piano music to help me sleep. The sound is very bright. I hope my answer is of reference value to you.