Solid and well built. A good looker and great peace-of-mind upgrade when utilizing heavier spring loads.
Please note that it does not prime as smoothly as the plastic gearing. Spin primes and flip primes will no longer be an option. Also you'll want to reinforce your gear box with epoxy putty to ensure that the post holes don't strip out. (Happened to me once. required replacement of the plastic part)
Overall though, a very good upgrade and I do recommend it for blasters modded for more powerful spring loads.
I love the slingfire...and it's my second metal kit. Totally worth it