Speakon connectors are the standard for speaker conections in PA and sound reinforcement applications, and if you’re building or installing a system they’re the only way to go. You could buy the cable and connectors and put them together, or buy these excellent ready-made cable assemblies. Available in lengths up to 20m for every application:

Speakon Cable 2 Core 5m Cat WA-7100
Speakon Cable 2 Core 10mCat WA-7102
Speakon Cable 2 Core 15m Cat WA-7104
Speakon Cable 4 Core 20m Cat WA-7106