flat buttons and small round balls. need help with id

[ATpro5]

Hey everyone! Found these at a colonial site recently. Almost all the flat buttons have been dug. Went slow and pulled out a few more things. Need help with a item. The brass zipper looking object with iron on the back... Its definitely period seeing how theres no trash out here. Maybe someone with colonial item smarts can help me out.

 

[ATpro5]

Heres a close up of the item i need help with