This is a plastic insert to hold a cable in the center of a Tekbox TBCP2-500 rf current probe, along with a stand to hold the probe in place.

Current probes are used to measure and troubleshoot signals that are conducted over cables. The plastic insert is designed to fit snugly in the above probe, and keep the measured cable in a known position to help take stable measurements. You'll need to print two of the adapters. The stand is designed to keep the current probe in a fixed orientation during testing.