This is the Remington 10 round .22LR magazine for the Remington Nylon 77 rifle.
Factory replacement parts are manufactured to the exact same specifications and tolerances and use the same manufacturing materials as the standard ones which come with the rifle, ensuring excellent fit and reliable operation.
You can’t go wrong with having extra magazines, whether it’s for quick loading times at the range or in the field. Or, as a backup in case you lose one or drop one in the mud.