It's an Imperial-era award, actually:
This is the Prussian Landwehr-Dienstauszeichnung 2. Klasse [Landwehr Long Service Award 2nd Class] of the type awarded up until 1913.
The "F.W. IV" monogram is for King Friedrich Wilhelm IV. who instituted the Landwehr Long Service Award in 1842. (The monogram on the award was not changed under the reigns of the subsequent rulers.) The devices to the left and right of it are stylized Landwehr crosses.
I cannot comment on authenticity or value.