Human resources are a main production factor determining the sustainable development. prosperity and competitiveness of any business unit. industry or the economy as a whole. and labor productivity is a main indicator providing information on the efficiency and quality of this resource in the production process. https://www.roneverhart.com/Behringer-UL-1000G2-Wireless-In-Ear-Monitoring-System-US-584-to-608-MHz-p31393/