That's the x-over, confirming they are an early (Mk I) version. It's taken as a wiring reference should I forget how it all goes back together. I will be keeping everything pretty much as original as a first step. Once I have got used to how they sound I will consider upgrades such as re capping and even the tweeter upgrades. For now I will simply renew the puny internal wiring and the binding posts, as one of my posts is broken.