FARSEE mainly produces two types of eGo batteries: Auto Battery without key-press and Manual Battery with key-press.

Auto batteries have FS520 and FS530 series.

FS520 has the key-ring on the battery tube. FS530 doesn't have. Both of them work automatically without key-press.

Manual batteries have FS eGo and FS540 series.

New FS eGo battery with flat key-press will be done soon. It belongs to the manual batteries too.

FS540 has special MEGA size design. It can be named as screwdriver as it has the top screw to control the E-cig's on or off. FS540 has a key-ring too. You are welcome to try.