Kata-ha-jime
(single wing choke)

"From the rear Tori slides his right hand round the front of Uke's gi to take a grip on the top of Uke's left collar. (as far up the collar as is possible)Tori then slides his left hand between Uke's arm and body,lifting Uke's arm and securing the hold behind Uke's head.Tori then pulls on Uke's left collar rounding Uke's neck ,at the same time Tori applies forward preasure to the back of Uke's head with his left arm.Release when Uke submits."