  We quantify the amount of non-locality contained in n noisy versions of
so-called Popescu-Rohrlich boxes (PRBs), i.e., bipartite systems violating the
CHSH Bell inequality maximally. Following the approach by Elitzur, Popescu, and
Rohrlich, we measure the amount of non-locality of a system by representing it
as a convex combination of a local behaviour, with maximal possible weight, and
a non-signalling system. We show that the local part of n systems, each of
which approximates a PRB with probability $1-\epsilon$, is of order
$\Theta(\epsilon^{\lceil n/2\rceil})$ in the isotropic, and equal to
$(3\epsilon)^n$ in the maximally biased case.
