InCharge Black Office FlexThe InCharge Black Office Flex has many of the same properties as the InCharge Black Office model, but also features a unique property that is not immediately obvious. The seat is flexible and able to tilt 11 in all directions. This feature forces you to sit with an actively tight core, as it challenges your muscles and balance point. The flexible seat requires a little getting used to, as it's an alternative way of sitting. It is similar to sitting