To continue delivering the world-changing science that Diamond enables, the facility is being upgraded. The 3.5 GeV beam in the Diamond-II storage ring will be maintained by seven (or eight) RF cavities of a normal-conducting design with damped Higher Order Modes (HOMs) similar to those installed at the ALBA light source in Barcelona and the BESSY and MLS storage rings in Berlin. Three HOM-damped normal-conducting cavities are already installed in the storage ring and so four or (five) additional cavities are required. The scope of the contract is the manufacture, test, and delivery to DLS of four (or five) HOM-damped cavities resonant at 499.511 MHz, including cavity support frames to hold the cavities in the required orientation, and base frames which support two cavities and their respective support frames..