Most people will tell you to use monofilament, but I always like to use braided line because of its hook setting capability
Bottom compression
Now remember, fish will mostly feed up, not down in the water column

The FlexVent suspension system, certified by the American Chiropractic Association, has articulated shoulder straps, a rounded back panel, comfortable stitch lines and soft-touch chemise fabric Zippered main compartment has a sleeve for either a laptop or hydration bladder Front bungee system with multiple webbing-loop options can hold a jacket or other item Tool-carry loops Vertical, secure-zip center front pocket Secure-zip pocket on top lid Padded, vented shoulder straps with a mesh drop pocket on right strap and secure-zip phone pocket on left strap Two mesh water bottle pockets Adjustable waist belt Adjustable sternum strap with a whistle buckle Reflective details 210D Nylon Ripstop 420D Recycled Nylon plain weave Recycled 200D Polyester liner Volume: 28L/1709in Dimensions: 18.9x12.4x7.09in/48x31.5x18cm Features The FlexVent suspension system, certified by the American Chiropractic Association, has articulated shoulder straps, a rounded back panel, comfortable stitch lines and soft-touch chemise fabric Zippered main compartment has a sleeve for either a laptop or hydration bladder Front bungee system with multiple webbing-loop options can hold a jacket or other item Tool-carry loops Secure-zip pocket on top lid Padded, vented shoulder straps with a mesh drop pocket on right strap and secure-zip phone pocket on left strap Two mesh water bottle pockets Adjustable waist belt Adjustable sternum strap with a whistle buckle Reflective details Materials 210D Nylon Ripstop 420D Recycled Nylon plain weave Recycled 200D Polyester liner Specifications Volume: 28L/1709in Dimensions: 18.9x12.4x7.09in/48x31.5x18cm Volume 2 L

As I mentioned before, I saw a picture from this Teddy Ruxpin write up that showed a sensor taped onto the top of an Echo