It seems that I bought one of the last Picatinny rails for my CZ 452 earlier this year, as they are no longer offered by M*Carbo. This is a great addition to the 45x-series of CZ .22 LR rifles.
There is another brand that has an identical design, but it is 2-3 times more expensive than what I paid to M*Carbo. I see there is also a posting of the Marlin 60’s discontinued rail as well. I have 3 buddies that bought Marlin 60’s in the past year, and would love to have Picatinny rails for their scopes/optics. Please reply if anyone has a source for the Marlin 60 rails.