XS Scuba Worthington Cylinders HP Steel 3442 psi. Tanks
if you read all the description, I copied part of it here.....
During the process of Hot Dip Galvanizing, the exterior of our steel cylinders are submerged into 840°F molten zinc. The process deposits an 8 - 10 mil thick zinc barrier to protect against the corrosive ocean environment. This layer of zinc metallurgically bonds to the steel cylinder. It will not chip and wear away like a painted zinc finish. XS Scuba is so confident that exterior rust will not be an issue, we guarantee it for the life of the cylinder. If the exterior of your XS Scuba HDG steel cylinder rusts, we'll correct it for as long as you own the cylinder, without cost to you.
Steel Cylinder Features:
Manufacturing Process
Built from Chromium Molybdenum steel plates
Utilizes the deep drawn process; the preferred method to build a SCUBA steel cylinder
This process yields a cylinder with a very uniform wall thickness resulting in a lighter, more efficient cylinder.
buoyancy
Superior buoyancy characteristics
These cylinders have been designed to be slightly negative at the end of a dive
Exterior Finish
A three-step, rust-preventative process
Consists of shotblasting, protective zinc coating, followed by a durable powder coat finish.
Interior Finish
Highly-resistant to internal rusting
Phosphatized interior
blah blah.... also notice that the 119s are $400. each......