Mart, if I am correct the Lightening plates being sold are aluminum and and then you place your silver on top of the aluminum, add hot water/ baking soda to cover the tarnished silver and the chemical reaction eats away the tarnish (and the silver). (People can do this with simple aluminum foil that they use in the kitchen!)
It is okay to use...but it eats away your silver and your silverplate is thin enough! Not recommended by silver lovers.