Unknown implants for full arch rehabilitation. What implant is that?

These 6 implants were placed back in 2016-17. The patient does not know what system they are and has misplaced all relevant records. The implants are about 4*12mm as measured on the IOPAs. 1.25 and 1.27 hex drivers did not work to unscrew the healing abutments. The healing abutments have 6511 and 6522 engraved on them. Kindly help identify these implants. I really appreciate any help you can provide. Thanks in advance.

1a87cd78-4181-4daf-a893-6a9ee96fd1f5

1a87cd78-4181-4daf-a893-6a9ee96fd1f5

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