Plastic Core is for easy rolling inside any dispenser!!! 50 ROLLS/20 BAGS PER ROLL = 1000 BAGS These bags are Thin, Strong Waste Bags Can hold up to 18 lbs Plastic Core Inside for easy rolling inside any dispenser Fit most dispensers on the market For Dogs of All Sizes Unscented Bag Specification: Color Black Bags in roll, pcs 20 Thickness, microns 12 Bag Size, in 12.5 x 8.5 Roll Size, in 2.25 x 1.25