You'll get a pvc suction cup by default with each accessory product. If you're happy with this, stick with what you've got.
If you want extra pvc suction cups they're here. Extra suction cups are useful if you have a shower dome so you can more easily relocate your bars into the fresh air from time to time. Nanotape won't work for this purpose but a spare Block Dock will.
If you prefer a natural rubber suction cup as a substitute or in addition they're here. Rubber suction cups do not fit the Hookups.
If you prefer to try a nanotape* backing as a substitue or in addition they're here.
Want to use your Block Dock on a flat surface? You'll need a Base. It fits all sizes.
*If you have a textured surface or one that is unfriendly for suction cups you might like to try the nanotapes (they come in twos). We can't guarantee it for all surfaces but it certainly works on more than the suction cups.