seat bottom cutout?

On my 9A kit, there is a prepunched rectangular cutout (both sides) a couple inches aft of the control stick opening, and I've yet to figure out what this is for. Is that for the crotch-strap attach brackets?

EDIT - a little searching and I found the answer, yes it is. Not sure I'll use the crotch strap right now but I'll go ahead and install the brackets regardless.

You are correct, crotch-strap opening.

I recommend installing the crotch straps.

These serve two purposes. 1) They hold the lap belt down in its proper position and 2) They prevent "submarineing" in case of a sudden stoppage. Submarineing can be very detrimental to "man parts" when meeting with the control stick!

Mel said:

I recommend installing the crotch straps.

These serve two purposes. 1) They hold the lap belt down in its proper position and 2) They prevent "submarineing" in case of a sudden stoppage. Submarineing can be very detrimental to "man parts" when meeting with the control stick!

Click to expand...

Valid observation, thanks for that.

Crotch strap

Also the only way to keep tall heads off the canopy, ask me how I know.