When entering the market to outsource infrastructure (Colo, IaaS, Managed Services, etc.) you will find a cornucopia of provider choices. While your unique selection criteria can be extensive here’s one quick way of getting some providers off your short-list; see if they define Service Levels as an Agreement or an Objective.
A Service Level Agreement (SLA) is a “negotiated and binding arrangement between parties as to a course of action.”
A Service Level Objective (SLO) is “a thing aimed at or sought; a goal or intention”.
Your end-users and executives expect more than an intention from you to deliver infrastructure services. Therefore, you should expect more than an intention or objective from your provider.