https://www.audubonstrings.com/pirastro-obligato-cello-a-string-4-4-size-medium-gauge/
Pirastro Obligato Cello A String - 4/4 size - Medium Gauge - Audubon Strings, LLC
https://www.strijkinstrumentenshop.nl/en/pirastro-permanent-soloist-cellosnaren-4-4.html
Pirastro Permanent & Soloist cello strings - BowedInstrumentsShop
Permanent and Permanent Soloist cello strings have a full and powerful sound, easy tuning and a smooth response. The strings are also suitable for electric cell
cello stringspirastropermanentsoloist