Do they fit a WielMcLean unit model number 383500631

These pellets are exclusively for use in JJM products, pH Power Pellets® are exclusive to JJM® condensate neutralizers.

Weil McLane recommends the 383-500-631 be changed as follows:

To the Owner: Condensate neutralizer tubes should be replaced every two years, or every 2,000 operating hours, or when PH level moves below 6, whichever comes first.