1. Constants in Ruby usually use ALL_CAPS with CamelCase used for Class/Module names (which are constants).  Just because Framework uses CamelCase constants all over the legacy code doesn't mean it's a good convention to follow.
2. Why not make this a Hash:

```ruby
INTEGRITY_LEVEL = {
  low: 'S-1-16-4096',
  medium: 'S-1-16-8192',
  high: 'S-1-16-12288',
  system: 'S-1-16-16384'
}
```

Or better yet, encode the pattern:

```ruby
INTEGRITY_LEVEL_KEY_PREFIX = 'S-1-16'
INTEGRITY_LEVELS = [
  :low,
  :medium,
  :high,
  :system
]

def self.integrity_level_key(integrity_level)
  index =INTEGRITY_LEVEL.index(integrity_level)
  multiplier = index + 1
  value = 4096 * multiplier

  "#{INTEGRITY_LEVEL_KEY_PREFIX}-#{value}"
end
```