Can Anybody guess how these Swimming touchPads work?

[Shahriar]

Hi

Today I saw these Swimming competition touchpads Manual (Attached file)
and I am wondering how these touchpads work!

it the Manual it has written :"The touchpads use a proven design incorporating three conductive plates made of  non-corrosive stainless steel to provide years of reliable service. The stainless steel front and intermediate plates fex easily when touched by the swimmer. Resilient strips of insulating acrylic  foam tape separate each plate. while the touchpads are highly sensitive across the the top and front, they are tough enough to keep wave action from activating the plate"

the Size of panel is 90cm x 240

I have attached the Manual too;

ThanX in advance
Shahriar

SL10421.pdf