A LocalSpecification comes from a .gem file on the local filesystem.

Methods
I
Instance Public methods
installable_platform?()

Returns true if this gem is installable for the current platform.

Source: show 

# File lib/rubygems/resolver/local_specification.rb, line 9
def installable_platform?
  return true if @source.kind_of? Gem::Source::SpecificFile

  super
end