Just got and tested one of these 5V modules, works fine. One control input, normally high, pulse low momentarily to toggle the relay. Just 1024 of these and you can DIY 1K of computer memory, the hard way!
"When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."
- Pablo Picasso