The Kondor Blue Sony FX3 Top NATO Rail is a great top handle or monitor mount alternative to the Sony XLR-H1 XLR Handle Unit. Machined from aerospace grade aluminium, the NATO rail is fully compatible with NATO standard.
The NATO rail mounts securely via two 1/4 20 holes built into the camera body. If you need to mount an accessory without NATO compatibility, there are also 1/4 20's and an ARRI style mounting options.