The AA-6 seed roller has six round holes, 15/32" (12mm) in diameter. Spacing is adjustable from 4-10” apart depending on seeder sprocket combination. Seeder rollers have slots/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.