The Velo Orange Grand Cru Brake Levers are simply really nice brake levers. They're lightweight, comfortable, and feature an exceptionally smooth lever throw.
Here is what you get in the package: two brake levers (left and right) and two sets of shims. Without the shims, the brake lever clamps are sized for 23.8mm grip areas for handlebars that are bar-end shifter compatible. Use the shims for bars with 22.2mm grip areas (most flat or upright handlebars).
There are two screws on the top of the levers. The screw that uses a 3mm allen wrench is the one that tightens the handlebar clamp. The 4mm screw adjusts the tightness of the lever actuation. The latter is pre-adjusted so you shouldn't need to mess with it. Over time, if you feel any slop, give it a bit of a tighten and you should be golden.
1) For handlebars with a 22.2mm grip area, put the shims on the bar's end with the flanges facing the stem.
2) Slip the brake lever over the shims. You may need to loosen the 3mm screw.
3) Slide the brake lever into the desired position along the bar and tighten the 3mm screw.
4) Install your cable and housing. Use the small set screw for your brake lever's reach adjustment. Screwing it in reduces the reach. Use the barrel adjustor for any fine tuning of cable tension while in the saddle.
5) Finish your cockpit setup and ride!