My favorite companion! I use it with ALL warframes.

Benefits:

• Build focused on taking a lot of damage so you can take your sentry on the most difficult missions without too many problems, steel path for example;
• Automatic item collection (mods, credits, ammo, etc);
• Converts any collected ammo to the specific type used in your weapons (aka "infinite ammo");
• Reload your warframe shields;
• Automatically destroys nearby item containers (I've earned hundreds of stars and many credits for this);