Plum has three binding models for the racing and crazy light crowd.  The Race 135, Race 145, and the Race 185.  To start, the number which the Race bindings are named is simply the weight which they come in at on the scales, per binding.  All of them nearly the same, but with a few key differences, setting them apart.  The Race 145 is the signature model for the guys out there.  The 145 is designed to have a slightly stiffer rear fork, made out of steel that has a forward release setting of about 8.5, and a lateral release of 7.5, which is suited to people over 70kg, tall racers, or more aggressive skiers.  The 135 differs as it has a 10g lighter rear fork made of titanium, but has a forward release setting of about 7, and a lateral release of 7.5.  Other than that the two are the same, and users can order both steel and titanium forks to replace whichever model Plum Race they have.  (Photo Above Left:  2 Race 145 red & orange, and the Race 185 in the back)

One complaint which most ski mountaineering racers have is that they can't adjust these race bindings to different boot sole lengths, in order to use a training boot and race day boot.  Enter the Race 185.  The Race 185 is essentially a Race 145 binding mounted on a cnc'd adjustable plate.  However, the Race 185's heel piece is actually 5mm lower than the 145's in order to accomodate the 5mm cnc'd plate, and making sure not to change the ramp angle of the boot in the binding.  (Photo Right:  You can see the Race 145 and 185 heel height are virtually identical, so the plate does not disturb skiing ramp angle or skinning heel height)

The real beautiful thing about these models are that the toes (77g no screws) have adjustable pin widths, in order to accomodate boots where the boot inserts are off center, wider, narrower, allowing the binding to be specifically dialed in to any boot toe width, custom or stock.  You can see in the photo's where the pins screw in, as I have yet to install them.  This can be a huge benefit when it comes to ensuring there is no additional load to the toe's springs, and also helps guard against pre-releases due to systems which have not clicked down properly.  The toe also has an automically locking toe piece, ensuring for insanely fast transitions, and shaves even more weight using only 4 front screws versus other brand's 5 screw design.  (Photo Below:  Toe without pins 'left' and pin insert 'right')

To look a bit deeper into the design, the binding is specifically designed to reduce any calf strain and fatigue, by raising the heel slightly to eliminating muscle fibers from being overstretched while working hard.  The binding ensures that a 27.0 (300mm) boot sits at a 7.73 degrees, the height is  specifically designed for use on flat rolling terrain as well as steeper skintracks with more switchbacks.  Racers should shoot for an angle between 7 and 8 degrees of positive ramp angle while skinning (heel higher than the toe) to find the most efficient skinning position.  The toe piece has an optional, screw on or off, crampon attachment for spring skiing use and speed traverses.  As there is no plastic on the toe piece, there is no risk of accidentally cracking anything, or breaking off crampon attachments while sliding on and off.

The Plum Race series are beautifully thought out, and engineered for speed, with less chance of user error.  These are easily a better choice for anyone who wants an extremely light weight binding, but also a system that holds the boot in during aggressive skiing, and reliability through simplicity in remote mountain ranges.  Keep in mind these are well designed race bindings, but the bottom line is that they will hold up to so much more, and I for one am excited to ski these as an everyday ski mountaineering binding as well as on the race course.  (Photo Left:  The Plum Race 145 heel piece, weighing in a 61g with no screws)