Remarkably, many of the comments about the models that house the caliber 215 PS make mention of the small size of the movement in comparison to the models that are powered by this movement. For example here: Patek Philippe Calatrava Ref: 5196
…This style effect is important because it allows to hide a problem inherent in this watch: the too small movement which powers it. Indeed, the 215PS caliber has a diameter of 21.9 mm which are more than 15mm less than the case diameter (37mm). The second hand is located too close to the center of the dial despite after all the reasonable dimensions of the watch. Patek Philippe chose two methods to make it less visible this imbalance:
…The 9-¾ ligne (21.9 mm x 2.55 mm) Ca. 215 movement is a visually unassuming piece of work. The center and third wheel bridge is nicely curved towards the balance cock but the shape near the jewels bears no relation to the wheels it supports, simply clearing the ratchet wheel and retreating. Clearly this is a subjective evaluation and there is some historical precedence for the shape of this bridge: it closely echoes a bridge from an original Antoine Norbert Patek pocket watch movement. Likewise, the cock for the fourth wheel and escape wheel is slightly awkward. To its credit, the bridge layout of the Ca. 215 results in excellent visibility of all the train wheels.
…the present movement, Patek Philippe calibre 215 PS, is not the best they’ve ever put in a Calatrava. As with the watch, there’s nothing really wrong with it, but it suffers in comparison to some of Patek Philippe’s superb vintage movements — like the caliber 12-400 — both in basic design and in finish.
Official caliber 215 PS info at Patek.com – click here