Numbers 16:39

“And Eleazar the priest took the brazen censers, etc.] The metal of which these censers were made is particularly observed, to show that they were fit for the use they were ordered to be put unto, namely, for a covering of the altar of burnt offering, which was covered with brass, that being very suitable, since fire was continually burning on it; and by this it appears that these censers were different from those of Aaron and his sons, for theirs were silver ones; the high priest on the day of atonement indeed made use of golden one, but at all other times he used a silver one f237; and so did the common priests every day, morning and night, when they offered incense f238, wherewith they…”

“the brazen censers . . . made broad plates to be a memorial--The altar of burnt offerings, being made of wood and covered with brass, this additional covering of broad plates not only rendered it doubly secure against the fire, but served as a warning beacon to deter all from future invasions of the priesthood.”