Strategic human resource management has four main components: 1) Human resources which are the primary asset and can provide a competitive advantage through knowledge and skills. 2) HR activities like programs, policies and practices that help gain an edge. 3) Plans and patterns to ensure strategy fit between HR and business strategies and across HR activities. 4) Purpose which is achieving organizational goals by adhering to strategies. Portfolio models involve collections of assets managed by professionals to provide advantages like research, diversification, rebalancing support and a long-term view.