The US Supreme Court on Thursday denied an application for stay of the order from a Michigan District Court refusing to block a ban on bump stocks.

Bump stocks are used to turn semi-automatic weapons into machine guns by using the “gun’s recoil to bump its trigger.”

The suit was brought by Gun Owners of America (GOA). They allege that the new ban is illegal and are encouraging their members not to turn in their bump stocks.

This comes after a Michigan District Court refused to grant a preliminary injunction of the ban. GOA argued that household items such as shoelaces and rubber bands can also be used to convert semi-automatic weapons into machine guns.

President Donald Trump promised to enact the ban following the shooting at a Las Vegas country music concert in 2017. Thursday’s news comes following another denial of stay for the bump stock ban earlier this week.