Yes the Protect-A-Bed Allerzip Mattress Encasements are 100% bedbug proof. If put on properly, the any bedbugs within the mattress encasement cannot get out or bite through the encasement, and no bed bugs from the bed frame or other parts of the room can get through it to reinfest the mattress. Our information does not state exactly what the materials are that make up the mattress encasement. Below is the information we have from the manufacturer. Certified 100% Bed Bug Proof by an entomologist laboratory. Ultimate allergy protection Listed as a Class 1 medical device with the FDA. Superior protection against bedwetting Dust mite barrier and allergy protection Protects against allergens such as pet dander, pollen and mold Breathable, waterproof and absorbent 100% white terry cotton surface Guaranteed NOT hot to sleep on Cool and comfortable Machine washable Fits most regular and pillow-top mattresses