The Nintendo Switch accessory that joins two Joy-Con controllers into a traditional gamepad shape is the Joy-Con Grip.
The grip is included with the standard Nintendo Switch package. Players slide the left and right Joy-Con controllers onto its rails, placing their buttons and sticks on opposite sides of a central handle. This arrangement makes the pair feel more like a conventional controller during television or tabletop play.
The Joy-Con Grip does not charge the controllers. Nintendo separately sells a charging grip that adds charging circuitry and connects by USB. That distinction causes a common mix-up, because both accessories have a similar basic shape.
The Joy-Con Grip is also different from the Nintendo Switch Pro Controller. The Pro Controller is a single dedicated gamepad with its own battery, while the grip simply holds two detachable Joy-Con units and lets users reuse the controllers supplied with the console.