Model 5751

Serial Number (SN) barcode label on bottom of unit contains 5751-xx-xxAG or 5651-xx-xxCG, or case design like the following:

Model 5651A/5651B

Barcode label on bottom of unit contains 5651-xx-xxA(F/G) or 5651-xx-xxB(F/G)

Model 5651

Barcode label on bottom of unit contains 5651-xx-xx(F), without an A or B

Model 5551A

Barcode label on bottom of unit contains 5551-xx-xxA

Model 5551

Barcode label on bottom of unit contains 5551-xx-xx, without an A