This is the 393 model, the upgrade to the 3421. I used it with a Tamron 150mm-600mm on my tripod with great results. From Manfrotto: Secifically developed for use with very long lenses on Monopods.
Key features: Friction base which enables the bracket to pan on Monopod, also can be used on a tripod. Two rubber hand grips plus rubber protection to prevent damage to lens when tilted to maximum. Variable center height adjustment in three steps. The item "Manfrotto 393 Heavy Telephoto Long Lens Support Bracket with Quick Release Plate" is in sale since Sunday, December 9, 2018.
This item is in the category "Cameras & Photo\Tripods & Supports\Tripod Heads". The seller is "mconvry" and is located in Abingdon, Maryland. This item can be shipped to United States.