Ed Huntress wrote:
...
In the US, there appears to be only one brand of over-the-counter
drain cleaner that is straight, powder NaOH (lye). It's Roebic Crystal
Drain Opener, and the main (or sole?) retail outlet is Lowe's.
...

I don't know about Roebic, but Drano has ingredients in addition to lye.
Supposedly they help the drain-clearing process, but are not so good
when used for other purposes. E.g., paint stripping. Straight lye is
good, Drano not.

Bob