This is a set of 20 rolls, each containing 100 electric roll screws (3.8 x 38 mm) for efficient work. - Product Name: Electric Roll Screws - Size: 3.8 x 38 mm - Quantity: 100 screws x 20 rolls - Manufacturer: Kokubu - Total Quantity: 2000 screws Set of 3 boxes Thank you for viewing. These are full-thread plywood screws. They were mainly used for fixing 9mm to 15mm plywood. They are roll screws, so they can be used with screw driving machines from various manufacturers, such as Makita Auto Screw.