Linked from
The 34 pages that link to Smartphone, each with the reason it gives.
ColtanRelated: Tantalum capacitors made from coltan-derived tantalum can appear in smartphones.
Memory cardRelated: Many phones accept microSD cards to expand local storage.
Secure DigitalRelated: Many smartphones use microSD cards to expand local storage.
StopwatchRelated: Smartphones provide stopwatch functions alongside ordinary clock and timer tools.