Double Bass The MYSTERY String, Help ID

[CelinderMotoMan]

I went to Elderly and played this no name Upright from the 50's, the strings were nice but no one could tell me what they were. They felt like nylon but were wrapped like a metal roundwound string. They had less tension that flatwounds but more than gut (and they certainly weren't gut).They have yellow silk wrapping at the bridge.

Anyone know?

 

[AMJBASS]

They appear to be Velvet Compas 360.