Before revision: M-Disc alternatives Optical Syylex Glass Master Disc: Blu-Ray 25GB Blu-Ray 50GB - Fabricated on demand at the cost of €1000 (EUR) per disc these discs use etched glass and are only typically degradable by physical or chemical damage, but not by normal ageing inside an archival environment.
After revision: andM-Disc alternatives Optical Syylex Glass Master Disc: Blu-Ray 25GB Blu-Ray 50GB - Fabricated on demand at the cost of €1000 (EUR) per disc these discs use etched glass and are only typically degradable by physical or chemical damage, but not by normal ageing inside an archival environment.