According to this illustration, A and B are installed with the same steering wheel.
The only difference is that A is using original sponge and B is using HIRO SEIKO small sponge.
With the same condition which is installed with same steering wheel, the one with smaller outer diameter requires shorter route to turn left and right 45 degrees each (90 degrees in total).
Which refers that HIRO SEIKO small sponge can make steering reaction quicker than the original sponge does.
※It is like the time a big wheel and a small wheel need when turning one round is different.
HIRO SEIKO Small Sponge can be installed on steering wheel from KO PROPO, FUTABA and SANWA.