The Park CT 4.2 is specially designed to work with the tight tolerances and narrow profile of 10 speed chains and most new, high-quality derailleur chains. The CT-4.2 is a powerful, precise tool designed to quickly and accurately remove and install chain pins. It is the most accurate chain tool Park has made to date.
The CT-4.2 Master Chain Tool replaces the CT-4 Master Chain Tool. The CT-4.2 will work with hour-glass shaped 8, 9, 10 and 11 speed chains. It also fits the asymmetrical Shimano chain designs such as Dura-Ace 7900.
Please note: The CT-4.2 is not compatible with Wippermann chains.
I own this great tool. It's precise and just what the doctor ordered when installing a new Campagnolo Record 10s ultra narrow chain! This tool is precise, built very very well, and is a lifetime tool -- pins are replaceable!
Pros: Highest of quality, fair price
Cons: Absolutely none
For the purpose of opening chains that will subsequently be closed with a master link only, this tool is fine. However, for driving in new chain pins it is unacceptable. Here's why. When driving a new chain pin, the back of the chain is supported by a flat surface with a hole in it to allow a new pin to move beyond the surface of the outer link plate, or for an old link pin to be ejected. On a Shimano chain tool, this hole is 4.15mm. On a Campy tool this hole is 4.25mm. The Park tool has a 6.25 mm hole. This excessively large hole provides inadequate support for the link plate, so the link plate is substantially deformed by the force of pin installation. Campy 11 is very obviously deformed, and Shimano/Campy 10 are also deformed, though less severely. The Shimano or Campy tools do not deform the link plates at all. Any careful mechanic would notice this and never use the tool again.
Pros: Works fine if opened link plates will be discarded
Cons: Unavoidably damages opened chain link plates