We have a new, very hyper active puppy who has no fear of climbing around in a moving car, so we needed something that would contain her safely in the back seat and yet give her enough room to move about. This fit the our needs perfectly. She can go from the seat to the floor, but she cannot get up in the back window or the front seat. She can still look out the window, but she couldn't jump out if the window were opened for some reason. Also, if we were ever in an accident and needed help, she would be restrained enough so that aid could get to us and her without risk of someone being bitten if she were overwhelmed with fear.The strap is tough enough that she would have a hard time chewing through it even if she had a bit of time to try, but I'm not sure a larger dog like my son's larger dog couldn't chew through it given enough time unattended.Having two of these straps means we do not have to change them between my husbands and my car, we just clip her in and go.