Wear and tear are eventualities for all machine parts. This does not mean that anyone's looking forward to replacing parts as soon as they purchased something, though. With pool cleaners, many factors affect every part's longevity, especially the parts that have direct contact with the pool surface. Case in point, pool cleaner brushes, and tracks easily gets affected by water temperature, water pH levels, the buildup of oils and sunscreens, and random debris on the pool. These tracks are made to last but with the combination of factors affecting its longevity, pool cleaner tracks can wear, tear, or stretch prematurely. Perform regular maintenance checks on your Dolphin pool cleaner to ensure that it's always in top shape. And when the tracks do need replacement, ensure that you are aware of the right parts to purchase. Take note, only several models have long and short tracks. There's a possibility that a Dolphin model with equal-length tracks can develop uneven tracks due to uneven wear and stretching. Here's the list of the models that use long and short gray tracks with part number 9985015: Maytronics Dolphin Apollo Maytronics Dolphin Atlantis Basic Maytronics Dolphin Endeavor Maytronics Dolphin Saturn Several listings include other Dolphin models but parts diagrams for these models show that they only need a pair of long gray tracks (part number 3295-133). Double-check the part diagram for your specific model to confirm the part number of the required tracks. Models that require long and short gray tracks should have parts number listed as either: 9985015, 9985015-R2, or MAY9985015. Take note that DIY pool cleaner track replacement is not for absolute beginners. You'll need to properly take apart and then re-assemble your pool cleaner in order to install these tracks. There's also the need to check other parts for signs of wear. Because of this, you may also need to replace either the drive pulley, guide wheels, or bear