bandwidth-unit setting in traffic-shaper

The "bandwidth-unit" option described in the KB below (also in CLI references) doesn't seem to exist at least on FG60E/60E-POE with 6.4.x while I can see this option on 1000D/1500D we have. Is this limited to some certain models?
https://community.fortinet.com/t5/FortiGate/Technical-Tip-Traffic-shaper-and-bandwidth-unit-display/ta-p/195197

6.4.9 on 60E-POE:

FortiGate-60E-POE (guarantee-100kbps) # get
name : guarantee-100kbps
guaranteed-bandwidth: 100
maximum-bandwidth : 1048576
priority : high
per-policy : enable
diffserv : disable
overhead : 0

6.4.9 on 1000D:

FGT1KDxxxxxxfg1 (guarantee-100kbps) # get
name : guarantee-100kbps
guaranteed-bandwidth: 100
maximum-bandwidth : 1048576
bandwidth-unit : kbps
priority : high
per-policy : enable
diffserv : disable
overhead : 0

Thanks,

Toshi