Uncovering and explaining how our digital world is changing — and changing us.

Gillette, the razor powerhouse owned by P&G, filed a lawsuit on Thursday against online razor seller Dollar Shave Club.

The suit, filed in federal court in Delaware, says Dollar Shave Club products infringe on a 2004 Gillette patent related to a razor blade with a “chromium-containing overcoat layer.” Gillette wants monetary damages and a court order to stop Dollar Shave Club from selling infringing razors. It’s not clear why the suit does not name Dorco, the South Korean maker of Dollar Shave Club’s razors and an equity stakeholder in the startup. (Update: P&G spokesman Damon Jones said, “[Dollar Shave Club is] actually selling the product and bringing it to market; that’s why they are named in the suit.”)

Jones said the company regularly does “market surveillance” — that is, testing of competitor products — and discovered in its most recent round of testing of Dollar Shave Club blades what it believed to be patent-infringing razors. The testing followed press reports of Dollar Shave Club “investing new money in product development,” Jones said.

A Dollar Shave Club spokeswoman declined to comment on the lawsuit.

Dollar Shave Club has raised nearly $150 million in equity investments and was recently valued by backers at around $600 million. The company launched in 2012 with a hit promotional video starring CEO Michael Dubin, and has used a mix of irreverent online videos, TV commercials and social media campaigns since then to attract a large customer base. Dubin said earlier this year that it had more than two million subscribers who receive razor blade shipments every month or every other month. The CEO also said the company was projecting at least $140 million in 2015 revenue.

Gillette introduced Gillette Shave Club last year and hired celebrities such as Giants quarterback Eli Manning to promote it in June ahead of Father’s Day.

Correction: The story has been updated to clarify that the patent in question is for a razor blade including an overcoat layer, and not for the overcoat layer itself.