PROGRESSIVE LINK HYDRAULIC THUMB Keep the pressure on productivity with AMI's Progressive Link Hydraulic Thumb attachment for excavators. Designed to provide constant pressure throughout the entire cylinder range, the Progressive Link Thumb achieves more than 180 degree rotation to easily reach and pick up objects close to your excavator. The extra linkage expands the thumb's reach across the bucket's entire rotation – including at full roll-out – to deliver superior material handling in the harshest conditions.