a life-saver

a life-saver

someone or something that gives you a lot of help when you are in a very difficult situation When you're stuck in traffic like this, a mobile phone's an absolute life-saver.
References in periodicals archive ?
military and a life-saver for patients, as well as a roadside drug detector.
It's a life-saver for the developer and a budget-saver for the company footing the bill.