Was at Walmart today in Clayton NC buying some of that Tula 9mm ammo on discount and found these. I bought one of these smaller units (same brand, different model)about a year ago and it worked great. I scanned it with Walmart app and it was $2.50 each. I have a USB power tester that shows output voltage, amperage and transferred mah. I am currently running tests on it to tell exactly what they will charge, but I am guess I should get between 1 and 1-1/2 full charges on my iPhone 6. Would be great for camping, anytime your out and about, power outage at the house. At $2.50 I would suggest you grab one. I will report my testings in a few days.