When your opponent is keeping their elbows extremely tight, back flat to the mat, their neck may be vulnerable for attacks. Here, switch to the X-Choke. Slide your lead hand across to the opposite side lapel, getting a deep grip. Take your other hand and slide underneath the established arm to the other lapel to finish the choke. Make sure to go underneath the setup arm as it will be more difficult for your opponent to defend the choke.
1) X-Choke Transition
2) X-Choke Finish