Consumer products, e.g., shaving systems and toothbrushes, are disclosed which have a replaceable portion, e.g., a shaving assembly or a toothbrush head, that is removably mounted on a handle. The consumer products described herein include keyed structures on the handle and replaceable portion, the relative placement of which creates a unique interaction between the two parts. This unique interaction may, for example, be used to provide a dedicated attachment system for each specific customer of the manufacturer of the consumer product.