Subplates are thicker and heavier than fixture plates, so they’re often used as permanent assemblies in horizontal milling machines. You can use them as a base for fixture plates or build setups directly onto them. Made from A36 low-carbon steel, also known as mild steel, they resist flexing under heavy loads and hold up to repeated wear. The holes are lined with a precision bushing and a threaded insert to help locate fasteners, so you can clamp parts accurately and securely. Both are hardened to resist wear, but you can also replace them. Subplates also come with a plastic chip plug in each hole to block debris when they're not in use.