I have this one and have used it every day since late 2017. I’ve used it camping multiple time as well with great success. The built in battery will recharge my AW3 at least 4 days in a row. I typically wear my watch to bed, so I only charge my AW for about 30-45 minutes in the morning when I’m getting ready for work and at night for about the same amount of time while I’m getting ready for bed. Works great. It’s nice to have the option to put my AW in the case and zip it closed to carry with me if I forget to charge it while I’m getting ready. Really handy.

Also has a USB port on the back to charge other devices with a cable.

Smatree Charging Case for Apple Watch Series 1, Series 2, Series 3, Series 4 (Original Magnetic Charging Cable NOT Included) https://www.amazon.com/dp/B019MS45B0/ref=cm_sw_r_cp_tai_nq8DDbPZF248M