A. Perfectly Fit: Our climbing ring replacement kit is compatible with Dolphin Robotic Pool Cleaners like M200, M400, M500, Nautilus, Nautilus CC Plus, DX3, DX4, DX6, Aquarius XL, Premier, Oasis Z5i. B. Great Value: The package comes with all four climbing rings 6101611-R4, also fit Sigma, Triton (old), Deluxe 4/5, Apollo Plus, Wave 65, Endeavor, Edge, HD, Saturn (old), Atlantis, Apollo, 3001, 2X2, Wave 2X2, Prowler 820/83. C. Premium Quality: Our replacements are made from PVA; ensure to last longer. They are perfect for maintaining your pool safe and functioning properly. D. Simple installation: Soak climbing ring thoroughly in water until they expanded and softened enough to install on rollers. Slide them in slowly and ensure that they are sitting in their designated space.