If you're working on a Honda Sportrax 400 – whether it's the TRX400EX or TRX400X – and you need a new carburetor body cover, this one's a direct match.
Part number 16160-HN1-003 is the factory style cover that goes over the top of the carburetor to protect it from dirt and debris.
It's a simple plastic piece, but if yours is cracked, warped, or missing, you'll want to replace it to keep your carb clean and running right.