Maple Leaf Crazy Jet 6.04mm inner barrel 410mm.
Interesting concept which uses a gap towards the end of the inner barrel which allows some gas to pass the BB and then accelerate in front creating a cushion of moving gas for the BB to travel within.
In theory this should then create an improvement in range and accuracy.
Please note that the finish on these barrels is changing to silver.
For more information see video here.