Each pack comes with a removable, adjustable waist strap. You must specify in the notes of your order if you want a small (fits up to 40"), medium (fits up to 50"), or large (fits up to 60"). If you do not specify a strap size, a medium will be sent. There are no exchanges on strap size if no size is specified, an additional strap may be bought for $5. You may also email me at AstralThread@gmail.com, or message me on Facebook or Instagram with questions.