316 grade steel is classed as "marine grade" and is generally the highest grade stainless steel available commercially and a higher quality level than our 304 grade steel, which is classed as "outdoor" grade.
Both are totally suitable for outdoor use but we do suggest that in coastal areas especially, where there is high salt content in the environment, then the 316 grade will offer the very best resistance to corrosion.
PLEASE NOTE though that even with 316 marine grade steel a degree of maintenance is required to regularly clean the salt content from the air off of the shower and avoid rust spots appearing. Even if that happens it is aesthetic rather than detrimental to the quality of the steel and can be cleaned easily with diluted vinegar solution or a preparatory stainless steel cleaner.
As with all outdoor water products in periods of cold weather, the showers water supply should have an isolation valve fitted and the water supply must be isolated and drained down fully (and all taps left in an open/on position). This is necessary to avoid water freezing, expanding and causing damage to the parts.
Call the Ingarden team on 01732 463409 for more information