Easy to use Bubble Level for Pipes, Fence Posts, Poles, Masts, Mounts, Satellite Antennas, and More Slips into the top of the mount / pole for ease of use and to ensure the item is perfectly plumb Bubble Level is 2' OD, and works with most 2' OD Pipes, or 1 4/5' ID Pipe/Mount Quick insert, and quick removal ABS Bubble Ring is designed to hold itself in place while using - no need for glue, bands, or magnets