These have been turned down by a machine shop so they'll screw into the ports in the head of my 5.3 ls engine. It was cheaper to have multiple senders done, so I bought five. Even so, my per unit price ended up being $30. I'm keeping one for a spare, so three are available. They fit tight, don't leak, and work great. They seal up with included copper washers. I've seen them for sale on one website for $70 but they're out of stock. $30 plus shipping.