1990A-F5 & 1991L-F5 Serial Number iButton is a r ed data carrier that acts as an electronic registration number for automatic identification. GYRFID provides Ibuttons, keyfobs, wristband for different use style.
 
IBT – ibutton ring only, metal component dia17mm × 6mm
TM - TM Keyfob with handle 
TM-R – magnet TM key, magnet ibutton with holder
WRA04- wristband with ibutton 

Features: 
Model number: TM
Material: ABS
Size: ibutton 17mm, Handle L40×W15mm  
Color options: Blue/red/black/white/yellow/green
Note: 

Personalization Support:  
• Laser Logo or UID
• Encoding

Application:
• Door lock system
• Guard Tour system  
• Security patrol
• Sauna door locks 
• Electronic door locks

Ic options:
1990A-F5: ReadOnly, Unique 48bit serial number 
1990A-F4 is mini size key, dia10mm x H4mm button, total is 38x15mm
1991L-F5: 1152bit secure read/write, nonvolatile memory