What the percentage is trying to express
An ALR percentage is intended to express how much unwanted ambient light a surface rejects under the seller or manufacturer’s test conditions. It does not describe every light direction equally, and it does not directly predict black level in your room.
Classic versus Black Series context
NothingProjector publishes the PET Crystal Classic at 85% ALR and the Black Series floor-rising screen at 95%. It simultaneously lists the Classic at 0.85 gain and the Black Series at 0.6 gain. That pairing shows why a single metric is not enough: the two surfaces are tuned differently.
When the 95% claim matters more
If you cannot dim overhead light and watch heavily during the day, stronger directional light rejection may be worth prioritizing. If you can control the room and want more brightness headroom, the higher-gain Classic may remain attractive.
How to compare responsibly
Use published specifications to identify intended use, then look for measurements or demonstrations performed under conditions similar to your room. Keep image size, projector brightness and seating angle constant when comparing.