A security device for preventing or inhibiting unauthorized separation of a first part (e.g., a cable filter device) from a second part (e.g., a cable signal source) includes a connector having first and second connector parts which are freely rotatable with respect to each other, the first connector part including a male threaded end for removable connection to the first part and the second connector part including a female connector end for removable connection to the second part. A cylindrical sheath extends in covering relation to the first and second connector parts and is freely rotatable with respect thereto. In the attached condition, the first and second connector parts are accessible for attachment and removal only with a specially configured tool.