Plastic Post Insert for Older Keg Posts. Most posts do not require these. These are made for John Wood Ball Lock Kegs, but they will also work on other posts that require them, including many Racetrack Kegs. In some cases this may not be the exact size, but this is the only one still made. We have always been able to make them work when fixing our kegs. You may have to file it down slightly. These have been very difficult to find, but we seem to have a good source for now. Many of the kegs that used these were made a very long time ago and we would recommend replacing this part and the poppet valve while the parts are still available. Because many of them are still in service with this origional part we would expect the replacement to last just as long (20+ Years), but we can't guarantee that.