21:50 Nov 4, 2011 

I found the following pdf on "the patent reversible key system" (of Kaba gemini S), which says that:


"The reversible key technology allows the key to operate no matter which way it is in the cylinder",

AND
"The reversible key is extremely difficult to copy. The code on the key is not made by drilling but by using a special type of milling which conceals the exact dimensiions of the code on the key. There are also millings made on the edge positions. This gives additional security against unauthorized key duplications."



www.gbd.rs/pdf/kaba_cilindri/Kaba gemini S.pdf



So, I think מפתח דו-צדדי מאובטח covers it well.