I bought these castor's for my Singer industrial sewing machine table. I was looking for castors that could be lowered onto, or raised off the wheels depending on the situation, and that had good reviews, this product seemed to cover all that. I only have two holes on each leg for mounting, so I installed them using those two holes, and they work really well, easy to raise and lower, and wheels around really nice. I had to slightly enlarge one of the holes to match my table leg pattern, but it wasn't that far off as is. I highly recommend this product.