  We study flops of Calabi-Yau threefolds realised as Kaehler-favourable
complete intersections in products of projective spaces (CICYs) and identify
two different types. The existence and the type of the flops can be recognised
from the configuration matrix of the CICY, which also allows for constructing
such examples. The first type corresponds to rows containing only 1s and 0s,
while the second type corresponds to rows containing a single entry of 2,
followed by 1s and 0s. We give explicit descriptions for the manifolds obtained
after the flop and show that the second type of flop always leads to isomorphic
manifolds, while the first type in general leads to non-isomorphic flops. The
singular manifolds involved in the flops are determinantal varieties in the
first case and more complicated in the second case. We also discuss manifolds
admitting an infinite chain of flops and show how to identify these from the
configuration matrix. Finally, we point out how to construct the divisor images
and Picard group isomorphisms under both types of flops.
