DETROIT—Free to produce generic versions of the product after DoorBlocker’s 20-year patent ran out last month, hundreds of businesses have begun distributing cheap, off-brand doorstops to retail outlets nationwide, industry analysts confirmed Tuesday. “Now that anyone can manufacture a doorstop without fear of legal challenges from the DoorBlocker company, we can expect the market to be flooded with tons of these low-cost knockoffs of the original door-impeding device,” said market researcher Paul Holbloom, naming brands like DoorHalt, SwingLock, PropStop, and Wedge as being among those that have gone on sale in just the past few weeks. “It’s likely DoorBlocker will keep some of its most loyal customers, but I expect that in the future we’ll see many opting for doorstops that are more economical and less of a status symbol.” Holbloom added that the expiration of DoorBlocker’s patent would have no effect on the sizable segment of the market that has always held their doors open with bricks or shoes.