Flat top 21700 batteries are cells with a flush positive terminal — the standard choice for battery pack building and integration.
On a flat-top cell, the positive end sits level with the cell body rather than having the raised "button" found on cells made for devices. That flush design is exactly what pack builders want: flat tops sit squarely against nickel strip for clean, consistent spot welds, fit snugly into cell holders, and pack tightly in series and parallel without the height and contact issues a button top introduces.
If you're assembling a custom pack — power tools, e-bikes, energy storage, or any series/parallel build — a flat top is almost always the correct terminal type. (For devices that require a raised contact, you'll want a button-top cell instead.)
Key features
Flush positive terminal for clean, consistent spot welds
Fits cell holders and packs tightly in series/parallel
The standard terminal type for pack building
Available across a range of high-drain and high-capacity 21700 cells
