Under the right thumb there are four buttons, one is the space key (shift, alt, space, ctrl).

When I got this keyboard I transitioned from a standard (non ergo) layout, and thought the thumb clusters would take getting used to. They felt surprisingly natural.

I found the ortholinear layout harder to get used to (the straight vertical rows the keys are laid in). For a long time when I wanted a `c` I got an `x`.