The Whirlygig system is a time-tested method of manhole riser/collar installation. It is size accurate, installs in minutes and leaves no doubt about quality control. Simply place a form on the manhole cone, trim the form to grade with the Radial Arm Trimmer, place the manhole ring, check accuracy and pour redi-mix. The system streamlines installation into a process that increases safety and ease of install, and works every time to produce a sturdy installation, even on slopes of steeper roads. 800/307-4263; www.wgig.us.