Maytronics Dolphin M500. One year. Bought it for the third brush that sits amidships between the two vacuum slots. Paid a little more for the M500 over the M400. That extra was a waste, as I NEVER use the bluetooth connection and NEVER manually "drive" the cleaner. Buying again, I'd get the M400 with all the functional advantages of the M500. BTW, I do not leave it in the pool. I put it in, run a 3.5 hour bottom and sides cycle, then take it out and rinse both the robot and the cable with soft water, then store it on its caddy on the back porch, covering with a chair cover after dry. Manual says you can set a schedule and leave it in the pool. No sir. I do not leave anything that costs that much in a pool of chlorinated (and salted if you count 1600 ppm as salted) water. A caution to some people. The M500 is heavy. I think empty it's around 20 pounds or so, but lifting it out of the pool, until it has drained, I'm sure it weighs 40 pounds (maybe not that much but it feels like it when I'm standing and leaning over the edge of the pool. I gently pull it up from the bottom by the cable until the floats reach the surface, then I grab a float and handle. Still heavy. But this sucker, especially with the extra fine filters, really cleans the pool. Even sucked up a bunch of Sahara dust that was washed in by the rain.