Although Blackout Fabrics are exactly that - they do not let light pass through them - it is important that Customers are not under the impression that the Perfect Fit system creates a total blackout solution. Even with blackout Roller and Cellular fabrics you should expect light ingress around the frame perimeter albeit to differing degrees based on the blind type.
Cellular is the most effective blackout textile offering around 90-95% light block. 100% is only possible with cassette blinds, a totally different product altogether. Perfect Fit is all about the framing system which allows a non intrusive, hole free window shade fitting solution, it is not a cassette system.