Mobile phone accessories
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Cases, which are designed to attach to, support, or otherwise hold a mobile phone, are popular accessories for many phones, particularly mainstream smartphones.
Case measures are based on the display inches (e.g. 5 inch display). There are different types:
- Pouches and sleeves
- Flip cases and wallets
- Screen protection and body films
- Drop and shock protection
- Leather Case 
Holsters are commonly used alone for devices that include rubberized padding, or are made of plastic and without exposed rigid corners.
A Standing case improves user experience, being specially recommended for multimedia, videos and audio. Folio case is a combination case and stand, and may include a keyboard (USB for OTG smartphones or bluetooth keyboard).
Heavy duty cases are designed to protect from drops and scratches.
Skins and design covers can serve for protection and personalization. These are the result of the relatively "naked" designs produced by manufacturers such as Apple, where the metal and glass components of the device are exposed and vulnerable to damage. They are distinct from holsters, in allowing use of the device while in the case, but in many instances include a belt clip or other device giving it the functionality of a holster. They are made of hard plastic, rubber, or in the newer market adhesive-backed vinyl pieces. Vinyl skins can be ordered on many websites and come pre-cut to fit your cell phone or another electronic device. Vinyl material may be calendared or cast, with the latter being more expensive. Calendared vinyl is expected to only be used for short durations while cast vinyl is used on a more long term basis. Calendered vinyl also tends to shrink in the heat, and fade. Cast vinyl avoids these problems, but costs up to 250% more (which still is not high). 3M has manufactured a cast vinyl product that they call "Controltac". This vinyl cover maintains a more glossy look and provides an air release channel that prevents bubbles during placement. The more popular is the cast vinyl because of the range of designs.
Customized phone cases use custom printing. Different companies have different methods of printing on cases, some utilize sublimation for printing on mobile phone cases, other methods include inkjet printed skins and Dye-Sublimation 3D printing methods.
Some phones have a replaceable cover. A release button on the cover lets it pop off to be replaced with the new cell cover. Phones that lack a replaceable cover can accept a slip on or snap on cover. These come in leather, vinyl, silicone, or hard plastic.
Anti-lost and selfies wireless companions
Antilost keychain can easily locate the cellphone through the GPS and Bluetooth low energy features of the smartphone. Once the user is out of range, both phone and companion will alert him / her. It also can be used to take selfie.
Some smartphones feature SD card slots (Usually the smaller Micro-SD variant). These, in combination with a compatible SD card, can be used to transfer files from one device to another, or simply to increase the storage capacity of the phone.
Additionally, many devices have USB On-The-Go and support USB storage, in most cases using either a special USB micro-B flash drive or an adapter for a standard USB port. Such adapters can also be used with various other USB devices, such as hardware mice and keyboards.
Chargers and external batteries
Cell phone chargers have gone through a diverse evolution that included cradles, plug-in cords and obscure connectors. However, more recent devices generally use micro-USB. (Apple devices still use proprietary cables, though the form-factor of their 30-pin plug used on older devices has shown up elsewhere.)
External batteries can be included in the case (power case). Also external batteries can include rubber suction.
Smart lenses are larger and more capable than the phone's camera, having optical zoom and other features. They connect to the smartphone by Wi-Fi and an app. They are compatible with most smartphones.
Smart flash can be used also for selfies.
HDMI and Projector
Micro USB to HDMI cables are used in smartphones with MHL.