Apart from the closeness of the serial numbers (both stamped upside down and with similar, triangle-shaped '4'), these two boxes are of the same dimensions, and have similar combs, constructed in two parts with square tips to the bass half and distinctive, bevelled false screw-heads. Even the well-detailed lid retaining hooks are identical. However, No.4181 has only 5 comb screws compared to No.4179's 7, and has no visible maker's mark (4179 has this on the base of the governor block), 4179 has been overhauled and plays very well, but 4181 needs work to both movement and case.