Signatone Tip holder
From Microwiki
From top to bottom:
- U-P-TB (UnvrslSrngLdTflnIsoltdPrbHldr): electrically isolated w/ spring tip holder
- U-P (UniversalSpringLoaded PrbHldr): non-isolated w/ spring tip holder
- S1-1: non-isolated w/ old style holder, screw tip holder