After receiving many PMs and emails on the Tank Solo XL which I covered below, here is a comparison of that and the Tank Louis Cartier XL. Basically the Tank Louis Cartier XL is the next level up from the Tank Solo XL - the LC retails for almost exactly double the Tank Solo in rose gold.

If the Collection Privee Cartier Paris were still in production, the Tank LC XL would be part of that line. It uses an ultra-slim Piaget cal. 430 movement.

On the other hand the Tank Solo uses an ETA 2892. Other mechanical Tank watches priced in between the Tank Solo and LC, like the Tank Anglaise, Francaise and Americaine, also use ETA movements.

In terms of size the watches are similar from the front. The Tank Solo measures 31 mm by 40.85 mm long while the Tank LC is 33 mm by 40.4 mm. Visually the Tank LC looks more refined as the case brancards are rounded, while the Tank Solo brancards are flat.

However, the view from the side is very different. The Tank LC is a mere 5.1 mm high, the thinnest watch in the Cartier collection. It is remarkably flat.

The Tank Solo is about 50% thicker at 7.65 mm high. That marked increase in thickness is not so obvious on the wrist because the Tank Solo case back is domed so it sits deeper into the wrist.

A more subtle difference is the colour of the stone set in the crown. The sapphire is synthetic and a brighter blue on the Tank Solo, while on the Tank LC it is natural and darker, almost black in some conditions.

Thought both are silver, the Tank LC has a darker tone dial than the Tank Solo. In addition the Roman numerals on the Tank LC are slimmer. And of course the Tank LC has no seconds hand, while the Tank Solo has centre seconds. Overall the Tank LC dial looks more refined.

Notably Cartier also chose different alligator hides for the two. The Tank LC has the standard large scale, so called "bamboo" type strap from the alligator belly, while the Tank Solo has the smaller scales from the alligator flank, which are perceived as being less expensive.

Despite the similar design and shared heritage, both of this watches are poles apart in terms of fit and finish. The Tank Solo XL is obviously a carefully designed entry level watch, while the Tank Louis Cartier XL is the quintessential refined, dress watch that Cartier does very well.

- SJX