This is from The American Revolution Institute's Facebook page. I like that we can see some details of its construction.
We are excited to announce the acquisition of an American “new construction” cartridge box. This rare survival was one of the most important accoutrements to a Revolutionary War soldier. Why? Because it held his ammunition.
The cartridge box is made of leather panels stitched together with a flap to cover the contents. Inside is a wooden block with twenty-nine holes to fit cartridges. Consisting of everything a soldier required to fire one shot from their musket, a cartridge held a measure of black powder to prime the weapon, plus a larger measure of powder to pour down the barrel, and a lead ball, all kept within a casing of paper that—after the ball was sent to the bottom of the barrel—was rammed down with the aid of an iron ramrod to seat the powder and ball ready to be fired. The box was designed to be worn over the shoulder by a long strap, which is no longer present.
This design for a cartridge box—differentiated from previous iterations by the phrase “new construction,” which appeared in George Washington’s writings—was produced beginning in 1778 and was a marked improvement on the older boxes, especially its ability to keep its contents dry. This example of the “new construction” cartridge box is believed to have been carried by Benjamin Hale of the Seventh Massachusetts Regiment of the Continental Army. The Seventh Massachusetts participated in the Battle of Saratoga, the Cherry Valley massacre, and Sullivan’s campaign.

