HP Quad Block w/Long Adjustment Screws Used on DCI Edge Series 4/5 Delivery Systems Used on DCI Edge Series 4/5 Delivery Systems Works with normally closed automatic Consistent flow control for handpiece pressure adjustments Higher output due to improved airflow Longer lasting diaphragm No internal cross-over of air or water Twin-Block dimensions, 1 1/2" x 1 1/2" x 1" Tri-Block dimensions, 2 3/8" x 1 1/2" x 1" Quad-Block dimensions, 3 1/8" x 1 1/2" x 1" Quin-Block dimensions, 3 3/4" x 1 1/2" x 1"