The R-24 seed roller has two rows of twelve round holes, 23/64" (9mm) in diameter. Spacing is adjustable from .5"-2.5” apart depending on seeder sprocket combination. Seeder rollers have cups/holes to cup the seeds to allow for singulation. Made from anti-abrasion plastic to prevent build-up of static electricity that causes seeds to stick together. This item is shipped directly from our supplier, please allow 7-10 business days for delivery.