Smartphones from the A series are the starter models from Oppo. These devices offer relatively good cameras for an equally good price. The Oppo A91 has a practical and clear screen. Other A models have a larger screen. These screens offer plenty of room when you watch a video, but they are also difficult to operate with one hand. The Oppo A53 and A72 have a large 5000mAh battery that charges quickly. On a full charge, these smartphones last more than a day and a half with average use. At Coolblue, you can purchase the smartphones from the Oppo A series as separate devices. The mobile phones are SIM-free, do it doesn't matter which provider you have a phone plan with.