These Adams suction cups have a long neck with gripper nubs around their circumference.
The Adams long neck suction cup with gripper nubs can be pushed into a drilled hole of a sign and each of the 4 x 1mm high nubs will ease back out to grip the back of the product (see technical drawing image for dimensions).
Each 47mm Adams suction cup has a weight loading of 3 pounds (1.36kgs).