It's a strap for holding water bottle cap attached to the bottle. To be printed out of flexible material.
Nalgene best 3D printer models・23 designs to download・Cults
▷ nalgene bottle cap 3d models 【 STLFinder 】
nalgene lid 3D Models to Print - yeggi
Narrow Mouth Nalgene Cap Tether by Inspector5, Download free STL model
water bottle cap 3D Models to Print - yeggi - page 2
nalgene lid 3D Models to Print - yeggi
Narrow Mouth Nalgene Cap Tether by Inspector5, Download free STL model
Nalgene Water Bottle Lid by kzlife76, Download free STL model
water bottle cap 3D Models to Print - yeggi - page 2