An apparatus comprising: (a) a shaft assembly defining a longitudinal axis, wherein the shaft assembly comprises: (i) a first coupling member , and (ii) a second coupling member , wherein the first coupling member and the second coupling member are configured to flex toward each other from a first position to a second position, wherein the first coupling member and the second coupling member define a pivot axis in the first position, wherein the first coupling member and the second coupling member define a longitudinal channel , wherein the longitudinal channel is wider in the first position than the second position; and (b) an end effector comprising: (i) an ultrasonic blade extending from the shaft assembly, (ii) a clamp arm configured to couple or decouple with the shaft assembly when the first coupling member and the second coupling member are in the second position, wherein the clamp arm is configured to pivot toward and away from the ultrasonic blade about the pivot axis when the first coupling member and the second coupling member are in the first position; characterized in that the first coupling member comprises a tab , wherein the tab extends over the longitudinal channel toward the second coupling member . (a) a shaft assembly defining a longitudinal axis, wherein the shaft assembly comprises: (i) a first coupling member , and (ii) a second coupling member , wherein the first coupling member and the second coupling member are configured to flex toward each other from a first position to a second position, wherein the first coupling member and the second coupling member define a pivot axis in the first position, wherein the first coupling member and the second coupling member define a longitudinal channel , wherein the longitudinal channel is wider in the first position than the second position; and (i) a first coupling member , and (ii) a second coupling member , wherein the first coupling member and the second coupling member are configured to flex toward each other from a first position to a second position, wherein the first coupling member and the second coupling member define a pivot axis in the first position, wherein the first coupling member and the second coupling member define a longitudinal channel , wherein the longitudinal channel is wider in the first position than the second position; and (b) an end effector comprising: (i) an ultrasonic blade extending from the shaft assembly, (ii) a clamp arm configured to couple or decouple with the shaft assembly when the first coupling member and the second coupling member are in the second position, wherein the clamp arm is configured to pivot toward and away from the ultrasonic blade about the pivot axis when the first coupling member and the second coupling member are in the first position; (i) an ultrasonic blade extending from the shaft assembly, (ii) a clamp arm configured to couple or decouple with the shaft assembly when the first coupling member and the second coupling member are in the second position, wherein the clamp arm is configured to pivot toward and away from the ultrasonic blade about the pivot axis when the first coupling member and the second coupling member are in the first position; <EOS>