Wikipedia: "An Alem (Arabic: أليم‎, Turkish: Alem) is a type of metal finial. Although the terms used are somewhat fluid, in Ottoman Turkish, the word alem means a military banner consisting of a tall pole (sap) with a silk flag or banner (sancak) topped by a metal finial (saifa). In modern Turkish, sancak can apply to the whole standard and not simply the fabric of the banner. The word alem came to be applied to the decoration at the top of the flagpole"

Obviously this is only that final part. There is script visible on it.