Manual toilet flush valves are sized to fit tankless toilets. These hand-activated valves have a spud coupling for attaching to a toilet spud. They typically require a high-pressure water supply to operate.,Manual flush valves are hand-activated valves for flushing tankless toilets and urinals. Also known as manual flushometers, these flow-control devices are a cost-effective alternative to automatic valves and have a lever or button that requires no power source to operate.