Wet Canvas Carrier. A unique item that can be a real blessing. The principle is simple. The top unit with handle attaches to a wet canvas. Then place another canvas, wet or dry, facing the wet canvas. The unit keeps the two canvases 1/2" apart. A second unit fastens at the bottom. Fits any size canvas. Empty, the unit will fit in the bottom of a sketch box.

The width is between 3-1/4" and 3-1/2" (depending on canvas widths. Pretty much tight squeeze for 3" portfolios.)
The length is 5-1/8" and the height is 2-1/2"