For the Rancilio 'Clever' valves only. These have the number 1 stamped on the front. 10701239 replaces 20112603, 11/11/2015. If your existing valve assembly includes two o-rings and a stainless steel spring seat inside the valve, you will need to throw those out and just use the PTFE stem seal included in this kit.
The cam and yoke of the new Clever valves are now made of PEEK, an exceptionally resilient colorless (a dye is added for to obtain the tan color of the yoke) organic thermoplastic polymer in the polyaryletherketone (PAEK) family and PEEK 450 PVX (with the addition of graphite, causing the black coloration of the cam).
WARNING: This product can expose you to chemicals including lead, which are known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, go to www.p65warnings.ca.gov.