Si aun no has instalado macOS High lo mejor es que te des un poco de prisa por que Apple actualiza todos los firmware de los Macs compatibles. Esta es la lista completa

iMac10,1 IM101.88Z.00CC.B0C.1705021259
iMac11,1 IM111.88Z.0034.B12.1705021416
iMac11,2 IM112.88Z.0057.B0D.1705021559
iMac12,1 IM121.88Z.0047.B33.1705101231
iMac13,1:13,3 IM131.88Z.010A.B1C.1705011311
iMac14,1 IM141.88Z.0118.B46.1705011412
iMac14,2 IM142.88Z.0118.B46.1705011513
iMac14,3 IM143.88Z.0118.B46.1705011514
iMac14,4 IM144.88Z.0179.B30.1705011718
iMac15,1 IM151.88Z.0207.B26.1705011718
iMac16,1 IM161.88Z.0207.B19.1705011046
iMac16,2 IM162.88Z.0207.B19.1705011413
iMac17,1 IM171.88Z.0105.B25.1704292104
iMac18,1 IM181.88Z.0145.B07.1705082121
iMac18,2 IM182.88Z.0145.B07.1705082121
iMac18,3 IM183.88Z.0145.B07.1705082121
iMacPro1,1 IMP10.88Z.0058.B00.1705091711
MacBook6,1 MB61.88Z.00C8.B0A.1705021739
MacBook7,1 MB71.88Z.0039.B1A.1705021813
MacBook8,1 MB81.88Z.0164.B31.1705021217
MacBook9,1 MB91.88Z.0154.B21.1704292104
MacBook10,1 MB101.88Z.0148.B00.1705090111
MacBookAir3,1 MBA31.88Z.0061.B12.1705022008
MacBookAir4,1 MBA41.88Z.0077.B32.1705022117
MacBookAir5,1 MBA51.88Z.00EF.B1B.1705011412
MacBookAir6,1 MBA61.88Z.0099.B52.1705011614
MacBookAir7,1 MBA71.88Z.0166.B29.1705011046
MacBookPro6,1 MBP61.88Z.0057.B1B.1705021138
MacBookPro7,1 MBP71.88Z.0039.B1A.1705021852
MacBookPro8,1 MBP81.88Z.0047.B39.1705101327
MacBookPro9,1 MBP91.88Z.00D3.B21.1705012105
MacBookPro10,1 MBP101.88Z.00EE.B17.1705012106
MacBookPro10,2 MBP102.88Z.0106.B1C.1705011311
MacBookPro11,1 MBP102.88Z.0106.B1C.1705011311
MacBookPro11,2 MBP112.88Z.0138.B38.1705011718
MacBookPro11,4 MBP114.88Z.0172.B23.1705011413
MacBookPro12,1 MBP121.88Z.0167.B31.1705011413
MacBookPro13,1 MBP131.88Z.0205.B21.1704292116
MacBookPro13,2 MBP132.88Z.0226.B24.1704292117
MacBookPro13,3 MBP133.88Z.0226.B24.1704292117
MacBookPro14,1 MBP141.88Z.0160.B00.1705082121
MacBookPro14,2 MBP142.88Z.0160.B00.1705082121
MacBookPro14,3 MBP143.88Z.0160.B00.1705090111
MacMini4,1 MM41.88Z.0042.B0D.1705021222
MacMini5,1 MM51.88Z.0077.B31.1705011214
MacMini6,1 MM61.88Z.0106.B1D.1705011514
MacMini7,1 MM71.88Z.0220.B28.1705011413
MacPro6,1 MP61.88Z.0116.B44.1705011717


Puedes comprobar el tuyo desde el menú manzana, en acerca de este Mac. Informe del sistema y comprobar si te coincide con estos.