THIS Travel Door Lock Works on Hotel Room Doors

Bad review, you have to try to open the door while it's unlock not when it's already locked LOL.

Where can I buy one ?

If you're going to use this, I would use it on the dead-bolt lock if you can. The deadbolt can usually only be activated from inside, but the main door latching mechanism can be operated from either side, and if the hotel uses electronic keycards, then this pretty much could fail to keep the door closed.

It works for me too, I have been using one for over a year

Piece of shit
You can’t hold with one hand!!!
Do not recommend

Need for my house for daily use bc the maintenance team keeps coming in without my knowledge or consent. Instead of knocking and waiting or calling me or just walking away and coming back after reaching me they take it upon themselves to open my doors and come in. Once while I was sleeping and woke me out of sleep to the point my head and chest hurt from the shock of it all.