Streamers display wind activity but little more.  To some, activity is comforting even it’ not offering anything except movement.  Several types of materials are available for streamers.  The lighter the weight the are more sensitivity but erratic.  The wind attempts to lift them and their own weight pulls them downward.   This is the true wind activity, it never blows in a straight line or for any length of time.  Sailcloth has a stiffness that counteracts or neutralizes much of the fluttering, but they still have the rise and fall action.  Because of the weight, Sailcloth reacts a bit slower than the lighter materials.   Attempting to determine how much wind speed from this action is a “GUESS”.  
Attachment of a streamer is usually accomplished with a clip through a hole in the tail.  The consistent motion potentially can enlarge this hole or damage the tail.  MTC uses a brass eyelet to protect the tail.  Some wind flags display the streamers being attached to the top or bottom of the tail.  Any attachment that is not within the area of the main shaft will be less accurate by adding twisting energy.   Long streamers offer a couple of potential problems, they can wrap around to post/stand or create so much leverage that the tail becomes ineffective.  If the streamer were independent of the tail, perhaps they would be more useful.   The streamer should not be the primary control of the wind flag’s attempt to display wind direction.
MTC did not accept the simple solution to this problem by attaching the streamer directly to the tail,  instead, we addressed this issue with an independent streamer.  It is only available for the Trackers.  It attaches to the lower section of the wind flag and utilizes the 1/4″ thru the hole with a 1/4″ x 12″ aluminum rod to hold and move the streamer away from the tail reducing any influence or control being placed on the tail by the streamer.   It can be centered or off-set for one or two streamers.  A lightweight streamer for gentle breeze and a heaver streamer for higher energy wind. With this, it is possible to better understand the speed and energy of the wind and determine if the wind is active or if the flag is just pointing at its last active position.