Section s_prod.
Variable A B : Setoid.
Structure Sprod : Type :=  {Sprod_l : A; Sprod_r : B}.
Definition Equal_Sprod (a1xb1 a2xb2 : Sprod) :=
Sprod_l a1xb1 =_S Sprod_l a2xb2 /\ Sprod_r a1xb1 =_S Sprod_r a2xb2.

Lemma Equal_Sprod_equiv : Equivalence Equal_Sprod.