Since they first hit the market, there have not been significant improvements in magnetic probe holder designs. The MPO Quattro Magnetic Probe Organizer changes that with innovative new features. First, its ModMag attachment design removes the biggest risk present with other probe holders on the market — the dreaded rusted magnet that so often crashes reef tanks. Other probe holders are made with fragile acrylic and are glued together. Over time, and without your knowledge, the acrylic swells and the glue separates, letting saltwater inside to corrode the magnet and then seep heavy-metal toxins into your tank. Don't put your entire reef and beloved animals at risk. The ModMag on the MPO Quattro is instead made from durable, inert, pliable ABS plastic, and is ultrasonically welded and double-sealed against water intrusion - using no glue. Two pieces essentially become one when assembled. On top of that, the innovative "Shake Test" feature of the ModMag always lets you test that your magnet is still safe and dry inside the enclosure. Probes in the MPO Quattro are firmly held in place by the patent-pending Slide-Loc silicone gasket system. Just slide in the probe and it's held in place with simple friction. No thumbscrews to get stuck, break off, or crack your probes. Included are two guide tubes used for keeping your automated testing system tubes, like those on the Trident, safely in place and not picking up air or debris from the bottom of the sump. Also provided is an adapter for enabling smaller temperature probes. But it doesn't stop there, the ModMag that attaches the MPO Quattro is also multi-purpose. It has slots, both inside and outside the aquarium, where a full ecosystem of optional accessories can be mounted. So, your MPO Quattro can be mounted inside your sump, and a camera can be mounted to the ModMag on the outside. Who knows what else might come since you and others can also take advantage of this mounting system with DIY creations or accessories from other 3rd-party makers.