Howa HPTM15-0053 Detachable Mag Black Polymer 5rd 7.62x39mm/6.5 Grendel for Howa 1500
http://www.tandktactical.com/shop/682146320084-howa-hptm15-0053-detachable-mag-black-polymer-5rd-7-62x39mm-6-5-grendel-for-howa-1500-15942
http://www.tandktactical.com/web/image/product.template/15942/image_1920?unique=6fce671
This replacement or spare magazine is compatible with Howa 1500.