Bitcoin ASIC price index: It usually indicates the TH index of ASIC mining rigs mining BTC.
68j/TH
Type of rigs: old generation
ASIC mining rigs examples: S9, T9, S11, T15, M10 & others old generation mining rigs
38-68 J/TH:
Type of rigs: Middle Generation
ASIC mining rigs examples: S17, T17, MicroBT,s, M20, M21, M32 etc
Under 38 J/TH
Type of rigs: very latest generation
ASIC mining rigs examples: S19, S19j, S19 Pro, MicroBTC, M30s, M30s+, M30s++ & up to date model.
Screenshot from:
theblock