• Serial No. 1878 Serial No. 1878
  • Serial No. 2101 Serial No. 2101
  • Serial No. 2251 & Pure Tone Trade Mark Logo Serial No. 2251 & Pure Tone Trade Mark Logo
  • Serial No. 2343 Serial No. 2343
  • serial no. 2738 serial no. 2738
  • Serial No. 3456 Serial No. 3456
  • Serial No. 3738 Serial No. 3738
  • Serial No. 4037 Serial No. 4037
  • Serial No. 4111 Serial No. 4111
  • Serial No. 45XX Serial No. 45XX
  • Serial No. 4692 & Pure Tone Stamp Serial No. 4692 & Pure Tone Stamp
  • serial no. 4724 serial no. 4724
  • Serial No. 4962 Serial No. 4962
  • Serial No. 5020 & Pure Tone Trade Mark Serial No. 5020 & Pure Tone Trade Mark