retention of title
A stipulation on a contract of sale that the right of ownership of the goods shall not pass to the buyer until the buyer has paid the seller in full or has discharged all liabilities owing to the seller. It is also known as a Romalpa clause, from the case Aluminium Industrie Vaassen BV v Romalpa Aluminium Ltd  1 WLR 676. Where such clauses seek to claim rights over goods made using the original products or otherwise amount to a registrable charge they will be void for want of registration at Companies House. They require careful drafting to ensure validity.