This is a Knex switchblade that has a trigger which makes a blade swing out. the blade is sturdy, it doesn't use many pieces, and the knife overall is very reliable.

Piece count:

Connectors:
Dark grey: 2
Light grey: 1
Red: 3
Green: 1
Yellow: 9
White: 6

Rods:
Green: 24
White: 12

Exotics:
Black Y connectors: 3
Black ball joint connectors: 1

Step 1: The Main Body

The part that the blade is held in.

Step 2: The Blade

The blade.

Step 3: Other Pieces

These will connect the different parts.

Step 4: Putting It Together

Connecting it all.

Step 5: Where to Put the Rubber Bands

Let's put on the rubbies.

Step 6: How to Use

Pull the blade around into the main body until it can't go any further, and then push the ball joint down so that the Y connector on the blade clicks into the ball joint.
To open it, push the white rod that the ball joint is on up with your thumb and the blade will swing out.