Another "What is it?"

I thought that I would check here before posting this item on my site.
Somebody sent me the photo at the link below, looking to identify the
object, it's 6" long, a star on both sides, bought at an antique show in
Islip New York, text on it reads "Warranted cork filled", and at the top it
looks like someone imprinted an "I":

Please let me know if you recognize it.

Kris Baker...

R.H....

Probably too small for boat protection, it's only 6" long and 4-1/2" wide.
The owner guessed that it could be a hand warmer since it fits nicely in the
hands but I still think the cork was used so it would float.

Below is the same picture plus an image of the other side, which shows a lot
less wear:

Dave...

Could it be a marker for the float line on a fishing net??

Nancy2...

I would think leather and water wouldn't be a very long-lasting
relationship. My opinion (I don' know nuffin 'bout it, actually) is
that is something related to a sport of some kind. Notice it is
guaranteed cork-filled. Cork not only floats, but it also absorbs
blows ....

It isn't at all like blinders that my grandpa had for his horses, BTW.

I think it's related to a musical instrument.....I just can't think right
now. Like maybe a drum?