Here is a reproduction horn push switch, the part does not have any branding on the button like the original. The part comes with a fixing screw.

Please check this is the part is correct for your model as there were various switches fitted depending on the year and the market the bike was originally sold.

There were a few different original Honda part numbers for this type of switch, here are some of them:
35250-130-620
35300-098-671
35300-045-700

Compatible with the following Honda models:

Z50J1 MONKEY FRANCE
Z50A (Earlier Models)
CT70 TRAIL 70 K0 1969 USA
CT70H TRAIL 70H 1970 CT70HK0 USA
CT70H TRAIL 70H 1972 CT70HK1
SL70 MOTOSPORT 1973 K1 USA
SL70K1 U.S.A
ST50 DAX ENGLAND
ST50 DAX EUROPEAN DIRECT SALES
ST50 DAX GERMANY
ST50 DAX NORWAY
ST70 DAX ENGLAND