I needed to wall off crawlspace gravel from the drain pipe but still have plenty of pathway for water and never rust or rot away. these can easily be mortered or glued on. default is fine even to stop "screening" gravel. though i can easily make the grate sizes something different. half of it goes inside the block for alignment and stiffening , the other half is to be glued or mortered onto the block. sold individually , but with optional bulk savings options
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