Check the listing for details. TL Reefs Magnetic Probe Holder. Condition: New. Listed at 24.95 USD. TL Reefs Magnetic Probe Holder This holder will keep all your probes secured and out of the way. - 1 hole is 0.65", for temperature probe. - 3 holes are 0.55" for other standard probes, such as pH, ORP, etc. - Strong Neodymium magnets combined with a grippy oring hold the box securely in place on aquarium thicknesses up to 3/4" - Magnets are completely encased in cell cast acrylic and will never get water in them. No worries about rusting magnets causing water quality issues. - Thumb screws on the front will lock probes in place. This holder will keep all your probes secured and out of the way. - 1 hole is 0.65", for temperature probe. - 3 holes are 0.55" for other standard probes, such as pH, ORP, etc. - Strong Neodymium magnets combined with a grippy oring hold the box securely in place on aquarium thicknesses up to 3/4" - Magnets are completely encased in cell cast acrylic and will never get water in them. No worries about rusting magnets causing water quality issues. - Thumb screws on the front will lock probes in place. eBay integration by