Even after studying photographs in detail and comparing specification tables it's sometimes unclear exactly why there is a price chasm between two apparantly very similar items. Certainly careful examination would answer most queries but in this age of online purchasing that isn't always possible.
What would be genuinely useful is for someone who owned both items to photograph and describe the difference in order that one might then make an informed decision. This is the first article in a series designed to do exactly this.
Assos' range of summer jerseys consists of three models. Discounting the Superlight sleeveless leaves the two here: the SS.Uno and the SS.13.
When confronted with the physical items it is immediately obvious which of the two jerseys is the range topper. The Uno is presented in Assos' oft-used windowed zip bag, this time white in colour, and the 13 making its value clear by way of a shining silver box with tissue paper insert. Examining them shows a couple of similarities - both models meet what I consider to be the essential requirements for a jersey - a full length zip, and both have the sometimes-a-fiddle zip garage with the familiar "Sponsor yourself" suggestion.
Fabric wise, both jerseys feature Assos' Plasma material, but in difference places. The majority of the Uno is constructed from this, with a stretchier spandex like textile on the sleeves and shoulders. The 13 uses Plasma on the sides and back, but the rest is s similar spandex which is slightly more matt in finish and supremely comfortable. In my experience the materials of both jerseys are noticeably more resistant to odours than more traditional fibres used in other jerseys.
Sizing is a major difference. The 13 in a large is the same as the Uno in a medium. Assos describe the 13 as having a closer fit, but for the equivilant size it's a great deal tighter. I personally find the Uno to be a perfect fit in medium and therefore went for the 13 in large. The shape is different too - the collar is lower cut on the 13, making it more suitable for warmer days, and the 3D Senso Mesh frame running down the back helps maintain the jersey's position on the body when the pockets are loaded.
At the rear of the jersey the Uno has the standard three pockets plus an additional smaller zipped one, and the 13 has five, albeit not as wide or deep. The zipped pocket on the 13 is in the center rather than on the right hand side as on the Uno. Both jerseys have a hole for a radio cable (if you're a pro) or iPod headphones (if your not). Two of the pockets on the 13 are on each side of the jersey and I found these ideal for stashing the plastic cleat covers for my Speedplays.
A bonus on the 13 is that the centre pocket is black, both outside and in, meaning a grubby tube or multitool can be stashed without staining the fabric. Annoyingly though the depth of the pockets is an inch or so less than the Uno, meaning anything moderately large like a folded tub or rain jacket sticks out of the top.
Turning to the inside, the gripper elastic at the rear on the 13 has tacky logos (in touch, not quality) and silver detailing, traits common to Assos' other "13" labelled items, whereas the Uno has elastic. Care is required as this can stretch in the wash.
In conclusion, both jerseys are perfectly suited to all round use but the lower collar and lass capacious pockets of the 13 makes it more tailored towards warmer days when one is travelling lighter.