LaMotte Calibration Check Disk - Spin Touch 6 LEDs - 1705 test-kit-type_FAS-DPD This O-Ring is approximately 18

This O-Ring is approximately 18 Inches in diameter

Also includes bronze wedge with stainless steel bolt and 1/4-20 UNC ground screw

This swimming pool solar cover is designed to fit a 18 x 33 foot oval pool

If installed below water

LaMotte Calibration Check Disk - Spin Touch 6 LEDs - 1705 test-kit-type_FAS-DPD This O-Ring is approximately 18This LaMotte Calibration Check Disk is used in the WaterLink Spin Touch with 6 LEDs. Calibration disks are not interchangeable. If you have the older desktop model plugged into a computer, this is not the disk you want. The Calibration Disk resets the LEDs in the meter so it can read all tests correctly. The Disk consists of a disk with a permanently attached cover. Do not fill the Meter Check Disk with water. Water is not used during the meter check