Polylok risers can be stacked on top of each other. There are screw holes on the inside of the riser to attach it to a Polylok adapter ring, another Polylok riser, and Polylok distribution boxes or catch basins. Our Risers can be cast into concrete or used with the Polylok D-Box. All of our risers have structural ribs on the inside preventing frost from adhering in frost prone areas. Polylok's Risers are the only risers on the market to offer this unique feature.
• Heavy duty structural rib reinforcement for extra strength
