Refer to this
Each x = 150Kb/s
CF 120x = 120 x 150 / 1024 = 17.578 Mb/s
SD 150x = 150 x 150 / 1024 = 21.972 Mb/s
The ratings are all done by the manufacturers under their so-call controlled tests. We should always take such rating with a pinch of salt.
But of course... all these are just specs... How fast it really can go will depends on the device itself....
wow :thumbsup: so well analysed!!!