Usb

dmesg

show disks

dmesg |grep ^sd. 

sd0 at scsibus1 targ 0 lun 0: <ATA, KingFast, T031> t10.ATA_KingFast_04xxxxxxxxxxxx
sd0: 114473MB, 512 bytes/sector, 234441648 sectors, thin
sd1 at scsibus4 targ 1 lun 0: <JetFlash, Transcend 8GB, 1100> removable serial.85xxxxxxxxxxxxxxxxxx
sd1: 7450MB, 512 bytes/sector, 15257600 sectors

Show DiskLabel

sysctl hw.disknames

hw.disknames=sd0:9axxxxxxxxxxxxxx,sd1:60xxxxxxxxxxxxxx

Show Disklabel sd1

disklabel sd1 

disklabel sd1 
# /dev/rsd1c:
type: SCSI
disk: SCSI disk
label: Transcend 8GB
duid: 60xxxxxxxxxxxxxx
flags:
bytes/sector: 512
sectors/track: 63
tracks/cylinder: 255
sectors/cylinder: 16065
cylinders: 949
total sectors: 15257600
boundstart: 64
boundend: 15257600

16 partitions:
#                size           offset  fstype [fsize bsize   cpg]
  c:         15257600                0  unused

Fdisk

kill everything