Fwd:MIMO cable synchronization accuracy

Hi everyone,
To synchronize two USRPs, I connect them and add the following code in
the slave USRP. -------------------------------
set_clock_source( ‘MIMO’,0);

I have got that the length of MIMO cable is fixed because the cable
delay is compensated in the slave USRP’s motherboard. So here is a
question that what is the time synchronization accuracy within USRPs
using MIMO cable?
Thank you in advance.