Stanley Black & Decker plans to add drones to its commercial security business, and is developing drone-based systems in partnership with a startup called Sunflower Labs, CNBC has learned.

Best-known for its power tools, Stanley Black & Decker generated some 18% of its revenue last year from security products including electronic locks, perimeter sensors and video cameras commonly installed at hospitals and on college campuses.

Sunflower Labs, a start-up based in San Francisco (with its research and development lab in Zurich) makes a flying home security system. Its first product, still being pilot-tested with early customers, is comprised of solar-powered “Sunflower Smart Lights,” software and aerial cameras.

A user arranges the Sunflower garden lights around the perimeter and pathways on their property. Sensors in the lights detect the presence and activity of people, animals or objects around the home. Sunflower’s software can determine if their presence is normal, unusual or uninvited, or for example, if a person is casing the joint, or sneaking up to a side-door.

When activity around a home is suspicious, the Sunflower system cues a drone to inspect more closely. The drones, which are basically flying cameras, dispatch from charging stations, then shine a light down and record video of unusual activity below.

Users can opt to share the video with private security or local police, said Alex Pachikov, CEO and cofounder of Sunflower with CTO Chris Eheim. “Old school systems frankly get ignored by police because there have been so many false alarms,” Pachikov said.

Along with their partnership to develop flying commercial security products, Stanley Black & Decker is investing in Sunflower Labs, alongside Silicon Valley venture fund General Catalyst, also an investor in Stripe, Airbnb, Jet.com and Kayak. The new funding of about $3.5 million brings Sunflower’s total capital raised to $6 million to-date.

An investor with General Catalyst, Niko Bonatsos, said he expects Sunflower to help Stanley Black & Decker achieve its broader goals, while gaining a foothold in a new market through the partnership. Stanley Black & Decker is looking to grow its commercial security revenue from $2.1 billion in 2016 to $3-4 billion by 2022.

PriceWaterhouse Coopers forecasts the market for security drones will surpass $10 billion in worldwide, annual revenue by 2020.