The 1925 Advertisement
A 1925 Tidskrift för Schack advertisement offered a 'Prima schackur' from F. Englunds Förlag in Stockholm for 15 kronor. The wording indicated the clock was in stock.
Not a Proven Model Name
'Prima' was a quality description rather than necessarily a formal model name. Unless a surviving clock carries the word as a mark, the safer name is simply a chess clock sold by F. Englunds Förlag.
Seller, Not Proven Manufacturer
The advertisement identifies the publisher as the seller but does not identify the movement maker, cabinetmaker, assembler, or switching-system designer.
Institutional Significance
Because the publisher was embedded in Stockholm organized chess, it could connect an unidentified maker directly to the players and clubs that needed tournament equipment.