The Beck Distribution Corp was a pioneer in motorcycle distributing sourcing OEM (original equipment manufacturer) and aftermarket parts and accessories for foreign bikes to suit American rider’s tastes. The company dates all the way back to the early 1900’s. I would estimate the helmet seen here is from the early-mid 1960s, but have yet to track down an exact date or model number. Vintage American Motorcyclist Magazines currently on Google Books gives hints to the popularity of this three-quarter style helmet and the Beck Corp itself during those early 60s. In 1969 Beck Distribution Corp merged with Arnley Brake Shoe Company and the name and logo were changed to reflect that. So if anything I can say this helmet is at least pre 1969.
An interesting thing on this helmet is in the liner and foam core. The dense foam core is constructed of two halves instead of a single piece. Also the liner that once held the soft comfort foam is made of a nylon material, which gives the helmet interior a nice sort of satin finish, but wouldn’t be very breathable or moisture wicking. It’s evident that later safety improvements replaced some of these designs quirks.
The reflective squares on sides and back are a common addition to helmets of the era. A lone sticker inside shows the size as S 6 3/4″ and Made in Japan. One theory I have given Beck’s business model is the helmet was produced by Arai and then stickered Beck by the distributor, but at this time that remains just a theory.
Basecamp Vintage & Archives 
I used to have one. One of the best helmet!
Nice. I love finding these old lids.