The manufacturer offers this Performance Yellow Combo Beam Lens as a replacement optic built for FLEX ERA 4 LED lights, and it swaps the stock lens for a yellow-tinted combo pattern (SKU 4270). The combo optic blends spot and spread output, which gives the light reach down the trail while still lighting the sides. Compared with a clear lens, the yellow tint is the main reason to buy it: the manufacturer says Performance Yellow lenses offer a purer, brighter yellow output, which suits everything from dusty trails to open, clear terrain. Buyers who mainly run through heavy dust or silt may prefer the darker Amber shields, which the manufacturer says excel in extreme dust or silt conditions. Performance Yellow lenses replace the lens inside the light rather than sitting over it as a snap-on shield.
For fitment, the lens is listed for the FLEX ERA 4 platform only, so confirm your light model before ordering. The lens protects the light's internals from the elements, and the FLEX ERA 4 light pod itself carries an IP68 rating. Owners looking for a combo-beam yellow lens replacement, a FLEX ERA 4 performance yellow swap, or a KC 4270 replacement lens will find this is the direct part for that job. KC's FLEX ERA 4 Master Kits now include both beam pattern lenses in the box.
The manufacturer states that the Performance Yellow lens is a direct replacement for the lens inside the light. The Amber option, by contrast, is a snap-on shield that works with a clear lens.
According to the manufacturer, Performance Yellow gives a purer, brighter yellow output for a broader range of conditions, while the darker Amber shield is aimed at extremely dense dust or silt, where its hue reduces glare.
The manufacturer says its FLEX ERA 4 Master Kits include both beam pattern lenses in the box, and the single-light Master Kit listing shows Performance Yellow combo and spot lenses as selectable options.
The manufacturer publishes a FLEX ERA bezel and O-ring instruction sheet for lens changes, so review that document before you start. Because the lens is a direct swap, the main gotcha is the O-ring: check that it is present, clean, and seated correctly before reinstalling the bezel. The Master Kit includes spare O-rings, which is useful to have on hand. The step-by-step procedure and tool list were not confirmed in this research, so follow the manufacturer's sheet for exact steps.
