These solid neoprene rubber strips are designed for use against fuel tanks to create air spaces around the tank, lessening the possibility of trapping moisture against the tank body.
This is especially prudent for metal tanks.

Spacing strips are required by federal law, however, when fuel tanks are held in place or supported by large surface area, tight fitting, slip-in blocks of foam or other plastic materials which are not fully bonded to the tank surface.
In these installations, spacers must be placed between the foam and the tank surface so moisture cannot be trapped against the tank surface.
Spacers are required to be at least 1/4" thick so liquid drops cannot bridge the gap.
Dimensions: 1/4" x 2" x 10 ft

Supports, chocks or straps, and the insulation material between these items and the fuel tank surface are not included in this requirement.

This product complies with the USCG requirements for air spacers.

These neoprene strips can also be used for gaskets, component padding, and under wire straps.
They can be cut to a variety of shapes and sizes.
These rubber strips may also have applications for spacing water tanks.