Liner I believe is made by westinghouse, theres just too much dust for me to see the logo properly. Along the outside of the shell theres also a lot of writing, most likely written there as a going away gift. The item "Korean War 503rd MP helmet" is in sale since Sunday, April 29, 2018.
This item is in the category "Collectibles\Militaria\Korea (1950-53)\Original Period Items". The seller is "evatroch_0" and is located in Austin, Texas. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, Sweden, South Korea, Indonesia, Taiwan, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Israel, Mexico, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Chile, Colombia, Costa rica, Panama, Trinidad and tobago, Guatemala, Honduras, Jamaica.