Digital photo frames range in size from tiny keychain-sized units to large wall-mounted frames spanning several feet. The most common sizes range from to . Some digital photo frames can only display
JPEG pictures. Most digital photo frames display the photos as a
slideshow and usually with an adjustable time interval. They may also be able to send photos to a
printer, or have hybrid features. Examples are the Sony S-Frame F800, that has an integrated printer on its back, or the Epson PictureMate Show. Digital photo frames typically allow the display of pictures directly from a camera's
memory card, and may provide internal memory storage. Some allow users to upload pictures to the frame's memory via a
USB connection, or wirelessly via
Bluetooth technology. Others include support for wireless (
802.11) connections or use cellular technology to transfer and share files. Some frames allow photos to be shared from a frame to another. Certain frames provide specific application support such as loading images over the
Internet from
RSS feeds,
photo sharing sites such as
Flickr,
Picasa and from
e-mail. Built-in speakers are common for playing video content with sound, and many frames also feature remote controls. Battery-operated units are also available for portable use. == Aspect ratio ==