Magnets hold the accessories in place, and Mashable described the process as «making them acutely aware of [their body]... and how poorly [they] sat in normal chairs.» (inc.com)
Genuinely can't recommend this enough we have an island which normal chairs just aren't high enough for. (philandteds.com)
It meant I wasn't sitting as rigid in a normal chair, and helped my posture as I sat more upright. (inc.com)