Buckle Outfitters 100 Pack of 5/8" Side Release Whistle Buckles Black
These whistle buckles are very popular for paracord bracelets and lanyards. The also work with webbing and other materials.  The whistle is integrated into the buckle, so when crafted into a paracord bracelet, you can have an emergency whistle with you at all times.  Great for outdoor activities and even for keeping with you in urban environments as well.  Slot width = 5/8 inch.  Length = 50mm (1.96 inch). Width = 22mm (.866 inch). 100 Piece Bulk Pack.