The iPhone 6 and 6 Plus received positive reviews, with critics regarding their redesign, specifications, camera, and battery life as being improvements over previous iPhone models. However, aspects of the design of iPhone 6 were also panned, including plastic strips on the rear of the device for its antenna that disrupted the otherwise metal exterior, and the screen resolution of the standard-sized iPhone 6 being lower than other devices in its class. Pre-orders of the iPhone 6 and iPhone 6 Plus exceeded four million within its first 24 hours of availability—an Apple record. More than ten million iPhone 6 and iPhone 6 Plus devices were sold in the first three days, marking another Apple record. During its lifespan, the iPhone 6 and 6 Plus sold 220 million in total, which makes them the best selling iPhone models, so far, and one of the most successful phones to date.