What is the thingie on the WBT Bananna Plug


I am looking at getting some bananna plugs, and in particular have noticed the WBT model 0645. It looks like it has an insulator or something plastic that protrudes from the front parallel to the bananna extrusion. Anyone know what this is? Looks like this will prevent the bananna portion from going into the receptacle, will it?

Also, any comments on this plug, where to get it, or other comparable connectors. Please, Bananna only because that is all my speakers will take, the have 4 bananna holes per speaker (no "spades are better" please because I can't use them).
Here is the wbt cite

http://www.wbtusa.com/wbt0645.html

Thanks in advance for your helpful comments and/or jokes!
south_park
Gunbei, you have got it right, and Motorpsychos I think has the solution I was thinking of, its good to see people with the same problem at least. No reason performance wise not to cut the plastic dealie off and use it anyway.
South_Park, isn't this great? In true Audiogon fashion, Alexander and Motorpsychos have solved your problem! Have fun.
Well, my "problem" is the same as everyone else here, wanting this stuff in the first place, so I don't know if that's fixed. But seriously, thanks to everyone for the assistance.
As was mentioned the 0645 is CE complient for Europe and yes the plastic piece is to prevent plugging them into a 240v outlet.You can buy these directly from WBT USA (this is Kimber as they are the importer) call 1-801-621-1500 they have all the WBT products.