These filters are made from acrylic and are supplied in double threaded metal mounts. The filter blocks visible light and transmits only infra red. Analysis shows it to be somewhere in bertween Wratten 88A and 87C. transmission is approx 775nm.
The bayonet types are not stackable as they do not feature a female bayonet at the front. Rollei bayonet I can be used with Yashica TLR cameras such as the 124G
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