Many record stores sell the ubiquitous yellow plastic adapters. Usually you can buy these in bulk, so you just install one in each 45 then never worry about it.
There are also reusable ones, some just a chunkier piece of metal or plastic, sometimes made as a promo for a label. They need to have an inner hole, which is the size of a standard spindle, and an outer diameter the same as the inner diameter on a jukebox-cut 45, also standard.
A web search for "45 adapter" will reveal both of these options.
A few tables have built in adapters, or some have an indent or peg on the plinth for storing a reusable adapter (see: Technics 1200) which may or may not be lost by the time the table reaches the used market. The first table PB posted has one sitting next to the arm.
« Last Edit: October 01, 2017, 11:01:00 AM by fullheadofnothing »
Joshua Harris
I Write the Manuals That Make The Whole World Sing
Kit Packer Emeritus