ShopTalk: Frequency Analyser Torque Arm

[donald . campbell]

Dear All,
I am over in Dallas visiting family and am looking to take some tools etc 
back to the UK with me (they are so much cheaper here). I notice that 
Golfsmith is offering their Frequency Analyser Torque Arm at $19.99 (down 
60%).Is this piece of equipment an essential or a bit of an add on?
Please excuse my lack of knowledge but the only contact I have with other 
club makers is through this site, which has been a font of knowledge and 
great entertainment. I di enjoy the duck tape jokes!!!! 

Thank you
Donald