They are good for making a room darker, but definitely not blackout curtains.
I found that the color really makes the difference on whether or not they are more effective or not. I got the yellow ones and you can definitely see the sun through even at midday when it's not that sunny.
Red And White Stripe Room Darkening Window Curtains With Grommet Top - Set Of 2 Panels, Each 52"X84" - DriftAway Mia Stripe Collection
52 Review
Dusty Pink Velvet Blackout Curtains - Melodieux Pom Pom Thermal Insulated 52X96 Inch (1 Pair)
41 Review
LUCKUP 100% Blackout Waterproof Fabric Window Roller Shades Blind, Thermal Insulated,UV Protection,For Bedrooms,Living Room,Bathroom,The Office, Easy To Install 20" W X 79" L(Grey)
46 Review
MIUCO White Sheer Embroidery Trellis Design Grommet Curtains 95" Long For French Doors - 2 Panels (2 X 37" Wide)
41 Review
Black Rose Garden Arch By Gardman R350 - 75 Inches Tall, 39 Inches Wide And 19 Inches Deep
41 Review
Add A Touch Of Elegance With Windiy'S 5.9' Artificial Willow Vines And Eucalyptus Garland - Perfect For Weddings And Home Decor
34 Review
White Metal Wedding Arch With Climbing Plants Decoration, Perfect For Garden Bridal Parties - Adorox 7.5Ft Arbor Set
45 Review
Pink Artificial Fake Wisteria Vine Rattan Hanging Garland Silk Flowers String Home Party Wedding Decor 43.2 Feet (12 Pack)
41 Review