Sentry 18A Brushless Speed Controller
The Sentry series of BESCs have an inbuilt battery cell protector.
By plugging the connector into the batterys charge port the BESC can ensure that the pack is balanced and that the pack never drops below a recomended level. This ensures your pack wont be over-discharged and destroy your battery.
Its the best way to protect your expensive batteries. Considering in most cases your battery costs more than your BESC, its a wise investment to get a Sentry.

Cont Current: 18A
Burst Current: 22A
BEC Mode: Linear
BEC : 5v / 2A (3A burst)
Lipo Cells: 2-4
NiMH : 5-15
Weight: 27g
Size: 45x24x11mm

User Programmable, both via controller and optional programming card. The programming card is an excellent item as it instantly tells the user the current settings and with a few simple clicks of the buttons, the user can change the settings and have graphical reassurance of those changes.
The programming card is an excellent Item and simple to use!