The Whites Fusion Thermal undergarment is slightly more bulky than the Fourth Element Arctic undergarment but is far warmer. It provides excellent mobility and has very little buoyancy. I have taken to wearing a Santi BZ200 vest along with the Thermal Fusion and have been very comfortable in high 40s and low 50s, even for dives lasting an hour or longer.
It will absolutely NOT FIT under a BZ200 undergarment. If you need to add more warmth, then layer your torso with a polartec vest or a BZ200/400 thinsulate vest.
It will absolutely NOT FIT under a BZ200 undergarment. If you need to add more warmth, then layer your torso with a polartec vest or a BZ200/400 thinsulate vest.