Early cylinders with plaster or cardboard cores are often impossible to play, due to the gradual swelling of the core material. This cylinder reamer is designed to accurately and evenly ream out the cylinder enabling it to properly slide onto the phonograph mandrel. The reamer is nothing fancy, but it works. Please note that this reamer is not designed for use with wax or Lambert cylinders, and any attempt to use it improperly will almost certainly result in the destruction of the cylinder in question! Detailed instructions included.