"Panzer Division Ring, with the inscription 'Jag.ABT 521', referring to the Panzerjäger (tank-hunter) battalion 521 of the German Wehrmacht

Pz. Jag. Abt. 521 was a German tank-hunter (panzerjäger) battalion that was formed in January 1944, during the later stages of World War II. The unit was initially assigned to the Eastern Front, where it was attached to the 9th Army and saw action in the battles around Leningrad.

In June 1944, Pz. Jag. Abt. 521 was transferred to the Western Front, where it was attached to the 5th Panzer Army. The unit fought in the Battle of Normandy, where it was involved in several engagements against the Allied forces. It later participated in the Battle of the Bulge, where it fought alongside other German units in an attempt to break through the Allied lines.

Despite its valiant efforts, Pz. Jag. Abt. 521 was ultimately unable to stem the tide of the Allied advance, and it was disbanded in April 1945, shortly before the end of the war.

Today, military memorabilia like the Panzer WW2 division ring inscribed with the unit's name are highly sought after by collectors and historians interested in the history of the Second World War. The ring you have may have been worn by a member of the Pz. Jag. Abt. 521 unit, or it may have been made as a commemorative piece for veterans or collectors after the war.