Probe Tube Holder ORP, PH, Temperature, Dissolved Oxygen - Aquarium Reef Marine 3D printed, 100% Plastic, no metal, nuts or magnets ! A cheaper alternative to your acrylic shop bought mounts. Fits glass or fixing surface up to 12mm think, secured by thumb screws. Secures probe from 8mm to 16mm in diameter, with securing thumb screw. Do not over tighten thumb screws, risk of stripping the thread, damaging your probe or cracking the glass. Options: Size of probe holder, number of holes. Colour, Black, Grey, White Fixing type, normal (horizontal) or euro-brace (horizontal) 3D printing options available from seller. Have a request, please direct message through eBay.