DETROIT (AP) — On the picket lines at a General Motors transmission plant in Toledo, Ohio, passing cars honked and striking workers celebrated a tentative contract deal by munching on 10 pizzas dropped off by a supporter.

They had carried signs for 31 days and demonstrated the muscle the United Auto Workers union still has over Detroit’s three manufacturers.

Details of the four-year pact weren’t released, but GM’s latest offer to end the monthlong strike included wage increases and lump-sum payments, top-notch health insurance at little cost to workers, promises of new products for many U.S. factories and a path to full-time work for temporary workers.

That’s a big difference from what GM wanted going into the talks: to slash total labor costs at its factories, which are about $13 per hour higher than at foreign automakers in the U.S.

Terry Dittes, the UAW’s chief bargainer with GM, said the deal offers “major gains” for 49,000 union workers who have been walking picket lines since Sept. 16. They’ll stay off work for at least a couple more days while union committees decide if they will bless the deal. Then workers will have to vote on it.

The deal shows that the union, with less than one-third of the 1.5 million members it had at its peak in 1979, still has a lot of clout with GM, Ford and Fiat Chrysler.

“I think economically the UAW will do just fine in this agreement,” said Art Schwartz, a former GM negotiator who now is a labor consultant in Michigan. “The union certainly still has power in this industry.”

The strike immediately brought GM’s U.S. factories to a halt, and within a week, started to hamper production in Mexico and Canada.