I got a bunch of it out of and old RF-4c that used it for ballast when
they removed caeras. They are little blocks about 1/2" x 1" x 1 1/2"
in size,,,,,,,and heavy as hell. They are coated with some type of
coating. We used to have a container about the size of a 3 pound
coffee can setting on the table, filled with them. We used to say to
new guys, Hey, how about sliding that can of blocks over here..they
would about push their shoulder out of joint trying to just slide that
can across the table. Been told as long as the coating is on them and
you do not drill, machine or weld on them they are safe. I use em for
weights etc when I glue up odds and ends.....

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Put some color in your cheeks...garden naked!