Pvc Blackout Light Blockers Window Blackout L-shaped strips are mainly installed on the side of curtains and blinds. Blocks light from entering from the sides of blackout curtains and sunshades, perfect for bedroom, home theaters, or nurseries. Reduce Light Leakage They are made of light-absorbing PVC plastic material. Blackout strips prevents light gaps from both sides of blackout curtains blinds and windows. Works on cellular shades, honeycomb blinds, roller shades and blinds, roman shades and more. It can create a dark environment for you, thus protecting your privacy and sleep quality.