Update: I've only been mowing for 2 months and one has already failed. I bought these for the front hubs of my lawnmower. They seem pretty smooth, but I remove the inner seals because the hubs have grease fittings. I was impressed by how easily the seals came off and how little grease got into them. I have a feeling they will snap the first time you try to lube their outer seals. I would recommend leaving both seals in place and only replacing them every two years rather than lubricating them annually.