This is the one I got: someone shared theirs but this was under $10 (not eligible for Amazon discount) and it came quickly with Prime. It also has a pocket where I put my work ID. Universal Phone Holder
You can buy one on Amazon, however I bought one of those and it ended up not being the best for me - I use a phone mount that clips right onto the handlebar of the shopping cart and it’s a lot easier personally, however whatever works for you is what’s best!
Link for cart mount: https://www.amazon.com/dp/B07FDR57V8/ref=cm_sw_r_cp_api_glc_fabc_1a3aGbRSP9SP6?_encoding=UTF8&psc=1
As long as you don’t have any heart problems, or major medical conditions, you can use it. I use this one: TENS 7000 Digital TENS Unit With Accessories - TENS Unit Muscle Stimulator For Back Pain, General Pain Relief, Neck Pain, Muscle Pain https://www.amazon.com/dp/B00NCRE4GO/ref=cm_sw_r_cp_api_glt_fabc_JS5EAEN1ETJ19TQ00WYR
I use it for about 45 minutes on my calves and on my lower back. I like to do stretches after I’m done. I use it about 3 times a week.
For those curious, a TENS machines will block pain signals from hitting the brain, making it numb for a moment to fit in some stretches and giving really great relief. It also releases endorphins, that “happy” feeling.