Need a safe source of hydrochloric acid 4% in US

I'm having trouble finding a source of HCL. Please send suggestions for US source.

Here is one source.

Thanks. I have a couple more questions about using HCL: I have MMS mixed according to the old recipe, which I have been using with equal number drops of 50% critic acid solution.
Can I still use a number of drops of my old MMS with an equal number drops HCL 4%?

Is there a difference between MMS and CDS?

Yes, you will use the same one-to-one ratio of MMS to activator; 50% citric acid or 4% HCL.

CDS is only chlorine dioxide gas (CLO2) in distilled water while MMS1, after the 30 second 'activation' period, contains mostly unactivated MMS (about 90%) which should continue activating in stomach acid.

Some sellers of CDS have added unactivated MMS to CDS claiming it 'stabilizes' it, but that will add more CLO2 when ingested. Therefore, you will not know how much CLO2 you are consuming because of the added MMS.

A google search turned up sciencecompany.com. They sell it in a couple of concentrations, which you could easily dilute to 4% yourself and save some money.