UnitedHealthcare Select is exclusive provider organization (EPO) with no coverage for out-of-network providers[6] UnitedHealthcare Select Plus is a preferred provider organization (PPO).[6] UnitedHealthcare Choice functions as a HMO plan with access to specialists,[6] whereas UnitedHealthcare Choice Plus is an HMO which allows for out-of-network coverage.[6] UnitedHealthcare Navigate, Charter, and Compass require a primary care physician referral to see a specialist[2] meaning that they are more restrictive managed care plans, similar to point of service plans.