The SiphonDaddy works with flexible cans with an opening between 1-3/8" to 1-3/4". The siphon tube must be able to reach the bottom of the can and works best when you use a 5-gallon plastic cans.
I have personally use Midwest cans. I will be adding more cans shortly as I evaluate them with the SiphonDaddy.
These are good replacement caps if you are using older cans and want to get rid of the spout. I recommend these because your old spout likely leaks or you may have lost the cap.
Please note the links above are affiliate links, and I will receive a small commission if you use the link. Feel free to just purchase directly from Amazon. I am motivated to sell SiphonDaddy's and provide these links to help you. I do not warrantee this referral or make any representation other than I have purchased these and they work well for the application.