the round ones usually have ink. the ones that look like rectangles about the size of a shoe horn usually don't have ink.

Are security tags filled with ink?

But there's an important reason security tags are filled with ink –– it can be a helpful measure for retailers and deter potential shoplifters. If an item with an ink tag is purchased at a store, the cashier will remove it with a special device called a detacher after the customer pays.

Is security tag ink permanent?

Security ink is permanent, which makes it difficult to get out of clothes. According to the Iowa State County Extension Office, treat the stain immediately and blot it rather than rubbing, which will only spread the mess.