Hi Rob,

These ones with the part number starting 03-7066 are all the same except for a small variance in the length.

http://www.rtbb.com.au/catalog/index.php?cPath=170_171&sort=2a&filter_id=15

I think the 03-7066-3 were the longer ones and the 03-7066-5 the shorter ones or it could be the other way around, I can't remember exactly.  I have a bit of an assortment of all of them. These will do the coils on your flippers, sling shots, pop bumpers and just about anything else in your embryon but they won't do the larger coils on any drop drop targets and if Embryon has them they won't do the small coils on the drop targets either.