Abstract: Devices and methods are provided for measuring and/or adjusting the distance between two opposing surfaces of a work space, such as two vertebral bodies separated by a disc space. A sizing device may include at least one distraction member, an actuator, and an actuator controller. The actuator controller is movable to move the actuator, with movement of the actuator changing the height dimension of the distraction member. The amount of movement of the actuator controller is generally linearly related to the change of the height dimension of the distraction member. The amount of expansion force applied by the distraction member is also generally linearly related to the amount of movement of the actuator controller.