David Wilson
Contributor
Certainly looks like the full foot and heel strap version of Beuchat's "Espadon Record Parallèles" fins. For vintage Continental European fins, there's a superb web page atAre these the ones you mention
View attachment 132505
PALMES - PLONGEE COLLECTION
and it features these fins both with and without heel straps:
Espadon Record Parallèles à sangles (heel strap version)
Espadon Record Parallèles à chausson (full foot version)
Espadon Record Parallèles à chausson et sangles (full foot and heel strap version)
The same web page has pictures of different versions of Beuchat's JetFin.