Used in digital data bus, video pair, MIL-STD-1553B (airborne/ground, primary/redundant), baseband circuits and in any application for "noise-free guarded" circuits.  They are not recommended for new designs.  MIL-STD-1553B permits designer discretion for use of concentric designs in lieu of the two-pin connector, ideal for situations where you need
a screened two cable connector that cannot be reversed as is polarity sensitive.

These are the same size as BNC and of course can be used in many other situations

Have to go as a parcel so a lot of the cost is that, if you need more please ask for an invoice as we could probably send 5 packs for same postage cost

male, female available