I think they are SRIX.
See;
https://books.google.com/books?id=oHJCAQAAIAAJ&pg=PA406&lpg=PA406&dq=silica-gel+iceless+system+for+refrigeration&source=bl&ots=yBsJQW5Cp0&sig=ACfU3U3pXWXVImL6dYTdlXXInunnf328qw&hl=en&sa=X&ved=2ahUKEwjnrPbby9vmAhWZLs0KHd8zCYwQ6AEwAHoECAcQAQ#v=onepage&q=silica-gel%20iceless%20system%20for%20refrigeration&f=false
-- Jon Miller For me time stopped in 1941 Digitrax Chief/Zephyr systems, SPROG, JMRI User NMRA Life member #2623 Member SFRH&MS
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