We have a few of the FT240-31 with 8-turns, 30cm length remaining - offered here at a slight saving over the current 9-turn version.
When you bring balanced feeder into the Shack, it's good practice to use a Choke/Balun to interface it to your ATU. This Choke allows you to connect 300 or 450-ohm feeder to your antenna tuner and is best suited for "indoor" use, ie: under the desk, right behind the tuner.
It's the same type of Choke found in our boxed G5RV offering and has been developed as it removes the need for a patch cable, can be used (with care) /P, and is cost-effective. Using a 1:1 Current Balun at the junction of balanced-feeder+coax is preferable, in most cases, to a 4:1 Balun - and certainly better than the internal 4:1 (voltage) balun found in many tuners!
For other lengths and ferrite types of this product, please see the ATU Choke product.