A movable member assembly , comprising: a body extending between a first end towards a second end along a body axis ; a movable member slidably disposed within the body , the movable member provided with a first position feature and a second position feature axially spaced apart from the first position feature ; and a sensor assembly disposed proximate the first end , the sensor assembly having a first sensor and a second sensor , configured to detect a position of the movable member by detecting a position of at least one of the first position feature and the second position feature , wherein: the first position feature is a first sheet defining a first reflection surface disposed proximate a first movable member end , the first sheet having a plurality of openings which extend through and interrupt the first reflection surface , and the second position feature is a second reflection surface that is spaced apart from the first movable member end ; at least one of the first sensor and the second sensor propagates a sonic wave towards the first reflection surface and the second reflection surface ; the sonic wave reflects off of the first reflection surface to form a first reflection wave and the sonic wave reflects off of the second reflection surface to form a second reflection wave ; and at least one of the first sensor and the second sensor receives the first reflection wave and the second reflection wave . a body extending between a first end towards a second end along a body axis ; a movable member slidably disposed within the body , the movable member provided with a first position feature and a second position feature axially spaced apart from the first position feature ; and a sensor assembly disposed proximate the first end , the sensor assembly having a first sensor and a second sensor , configured to detect a position of the movable member by detecting a position of at least one of the first position feature and the second position feature , wherein: the first position feature is a first sheet defining a first reflection surface disposed proximate a first movable member end , the first sheet having a plurality of openings which extend through and interrupt the first reflection surface , and the second position feature is a second reflection surface that is spaced apart from the first movable member end ; at least one of the first sensor and the second sensor propagates a sonic wave towards the first reflection surface and the second reflection surface ; the sonic wave reflects off of the first reflection surface to form a first reflection wave and the sonic wave reflects off of the second reflection surface to form a second reflection wave ; and at least one of the first sensor and the second sensor receives the first reflection wave and the second reflection wave . the first position feature is a first sheet defining a first reflection surface disposed proximate a first movable member end , the first sheet having a plurality of openings which extend through and interrupt the first reflection surface , and the second position feature is a second reflection surface that is spaced apart from the first movable member end ; at least one of the first sensor and the second sensor propagates a sonic wave towards the first reflection surface and the second reflection surface ; the sonic wave reflects off of the first reflection surface to form a first reflection wave and the sonic wave reflects off of the second reflection surface to form a second reflection wave ; and at least one of the first sensor and the second sensor receives the first reflection wave and the second reflection wave . <EOS>