How to Value a Service Business

I've spent some time looking at B2B services with secure installation companies, fire companies. Given that that recurring revenue component could arguably help manage the transitioning into a new acquisition. Some of the things that are interesting about those companies also make them quite popular for low-middle market private equity companies or strategic buyers just looking to buy up the contracts. So it's pushing up those multiples. I'd be curious to know kind of how you value and how you're seeing multiples in the engineering and manufacturing side of things.