Those handpieces are specially designed to work on the 11s. The compact, long and narrow head with a limited height (0.4 inch) facilitates an optimum access in the back of the mouth.
Different handpiece’s lengths and shapes and 3 head protection options are available allowing you to design your own handpiece.
This instrument can not be sold without protection.
Find here the operating instructions
JORGENSEN ref.: J1414d9cx