XMark Premium Vinyl Coated Kettlebell XMark Premium Quality Solid Cast Iron Vinyl Coated Kettlebell - 40 lb. Single These one-piece solid cast iron kettlebells are hand crafted and coated with a tough premium vinyl. The rounded handles have spacious openings fitting comfortably into the palm of your hands. It is no secretXMark kettlebells are higher quality. You will not regret purchasing XMark kettlebells. Thank you for choosing XMark.