The Kirby Rug Protector Pads were/are used to put under the legs of heavy furniture that could not be moved, such as China Cabnets, heavy Sofa's,Console TVs, ect.
The Kirby Instant Sudz (recommended for use with the Rug Renovator System in those days) was alkaline, and could cause a reaction to metal and wood stain and could leave a stain on the carpet,Especially if the carpet being renovated were light, or white. These pads were furnished to act like a sponge,and soak up any residual foam from the Renovator before it could cause a reaction to metal or wood stained furniture legs and leave a nasty stain on the carpet. Wheather it really worked or not i dont know.