Systems and methods for object size estimation

A medical device, comprising:

• a handle assembly including an actuator;
• a sheath extending between a proximal end and a distal end, the proximal end of the sheath being coupled with the actuator;
• and
• an end-effector moveable relative to the sheath between an extended configuration and a retracted configuration, the end-effector including a plurality of expandable legs, each of the plurality of expandable legs including a plurality of first indicia and a plurality of second indicia;
• wherein each of the first plurality of indicia has a first color;
• wherein each of the second plurality of indicia has a second color different from the first color;
• wherein (i) each of the first plurality of indicia, (ii) each of the second plurality of indicia, or (iii) each of the first plurality of indicia and each of the second plurality of indicia includes a physical attribute extending radially outwards or inwards relative to a longitudinal axis of the respective leg, and
• wherein a length of each of the first plurality of indicia and a length of each of the second plurality of indicia are substantially the same, and the length of each of the first plurality of indicia and the length of each of the second plurality of indicia is between about 0.5 mm and about 3.0 mm.