A 2MM*6MM AT-26 Cylinder Crystal is a tiny, cylindrical quartz resonator used for precise timing in electronics, featuring a 2mm x 6mm size, often labeled as AT-26 or DT-26, providing stable frequencies (like 32.768kHz or MHz) for wearables, IoT, and wireless devices, known for compactness and reliability. 

In Simple Terms:
It's a miniature electronic component that vibrates at a very specific, stable frequency when electricity is applied, acting as a precise "clock" for electronic devices, especially where space is tight. 

Where to Find Them:
Electronic component suppliers like Newark Electronics, Acrystals, Farnell, AliExpress, Made-in-China.com, and eBay sell these crystals.