Universal Sensor Holders - Econo Starter Kit. The only adjustable bite block that holds most digital sensors in both the anterior and posterior positions. One bite block per patient for an entire exam. Change on-the-fly with a simple push of a button and a quick reposition of the sensor. Econo Starter Kit - 2 Large and 2 Medium Bite Blocks, Positioning Arms (1 Anterior, 1 Posterior), Aiming Rings (1 Anterior, 1 Posterior), 25 Comfees Deluxe Sensor Sleeves. Econo Starter Kit