Extech EX050 ExStik 16-Feet Extension Cable with Probe Guard/Weight For Extech DO600 Meter Extension cable for measuring in solutions that are hard to reach Optional 16ft (5m) cable with probe guard/weight Attaches to ExStik meter for taking remote measurements Helps keep electrode submerged and protected in liquid samples Not compatible with PH100 and PH110 meters and PH105, PH115 flat surface pH electrodes