The Grenztruppen were the East German border guards, in charge of defending the East German border from the West.
At its peak, the Grenztruppen numbered around 47,000. After the Soviet Border troops and the Polish Border Protection Troops, the Grenztruppen were the largest border force from the Warsaw Pact countries. 
These cuff titles would be worn on the left sleeve of the dress uniforms. 
 
These are original and unissued. Perfect to add to your East German collection.