I bought an OM OM-3 camera, This camera has a bluetooth shutter release (RM-WR2) that unfortunately is not for sale in the USA. The OM-3 unfortunately does not have a wired shutter release port. It does have the option to allow the phone app (OIShare) to remotely control the shutter, but I find in some cases, I prefer not to use the phone.
I discovered the JJC adapter for the Leica X2, and I took a chance. It works perfectly for the OM-3.