WHOOP Battery Pack 4.0 You’ve got goals and so do we—like keeping you charged wherever your day takes you. Get continuous data for days on a single charge with our waterproof* battery pack that enables you to charge on the go while you wear it. To charge your WHOOP 4.0, simply slide the battery pack on your device to charge on the go. Use the included USB cable to recharge your battery pack from a laptop. Do you have an FSA/HSA? Take advantage and save on your WHOOP 4.0 Battery Pack. Just purchase the WHOOP 4.0 Battery Pack with your credit card and submit a reimbursement through your FSA/HSA provider. See how to file a claim/submit a reimbursement at https://www.fsafeds.com/file . WHOOP device and membership not included. *IP68 dust-proof and water-resistant up to 1 meter for 2 hours.