6K399-L inner corner is a plastic corner piece from Schwinn Hardware that joins two aluminum L-channels at an inside corner, so you get a continuous transition where the profiles meet instead of a visible cut edge. The dark bronze color matches dark bronze aluminum channels, which keeps the corner visually consistent on cabinet and fixture projects where the metal trim needs to read as one line. The 13/16 inch width defines the visible span across the corner, so you can plan channel layout and panel reveals with predictable coverage. Because the piece is plastic, it provides a clean molded geometry at the corner, which helps avoid sharp metal edges on exposed channel intersections. This corner piece is designed to work with ALU L-channels, so it supports trim layouts that follow room corners or casework returns without changing channel type.
The inner corner is designed so you can make a straight cut to each aluminum L-channel instead of cutting miters, which removes an angle-cut operation from the workflow and helps keep preparation consistent across multiple pieces. Two channel lengths fit into the plastic corner piece, so each run terminates in a square cut that seats into the connector rather than relying on precise miter alignment. This arrangement helps reduce gaps that often appear when hand-cut miters vary slightly between pieces. The straight-cut approach also suits jobsite tools that favor quick square cuts, so installers can trim channels to length on basic saw setups and still get a finished corner. Because the corner handles the geometry, the L-channels stay standard along their length and do not need profile modifications at the meeting point.
This Schwinn inner corner is specified for ALU L-channels, so it belongs wherever those aluminum trims turn at room or cabinet intersections and need a controlled meeting point. The dark bronze aluminum channel corner color targets projects using dark bronze anodized or coated channels, so the plastic corner visually integrates into the metal run on casework, displays, or furniture trim. Its placement at inner corners means it picks up the transition where two channel legs meet, allowing each leg to run straight into the connector rather than bending or deforming the aluminum. The 13/16 inch width defines how far the corner spans across the face, so designers can relate it to channel leg lengths and door or panel edge reveals for consistent proportional detailing across a run.
The plastic corner piece allows each aluminum L-channel to terminate with a straight cut, and that fixed geometry gives the connector control over the corner angle instead of relying on manual miter accuracy. By accepting two channel lengths into a molded form, the connector maintains a stable 90-degree transition, which supports repeatable corners when fabricating multiple cabinets or fixtures to the same layout. Using an inner and outer channel corner piece from the same design family keeps the joint language consistent wherever channels turn, so different cabinet elevations can share the same visual detail. Because the material is plastic, it is shaped to nest around the channel profile, which stabilizes each leg of the L-channel at the corner and reduces twist that could telegraph as uneven gaps along adjacent doors or panels.
The 6K399-L inner corner joins two aluminum L-channels at a corner, so straight-cut channel ends connect into a finished transition instead of leaving exposed metal edges.
The plastic corner piece is designed so two straight-cut aluminum L-channel lengths fit into the connector, creating a stable corner without cutting and aligning miters.
The dark bronze aluminum channel corner supports ALU L-channel runs on cabinets, fixtures, and trim layouts that use dark bronze channels around inside or outside corners.
The 13/16 inch width defines the visible span of the corner across the face, so channel placement and panel reveals can be planned around that coverage dimension.
The web description notes that the corner piece allows finished inner or outer corners, so one part can handle both inside and outside L-channel turns.
The dark bronze finish is stated to match dark bronze aluminum channels, so the joint reads as a continuous line where the plastic corner meets the metal profile.
This Schwinn 6K399-L inner corner in dark bronze plastic is built to connect ALU L-channels with straight cuts, so channels can run to every inside or outside turn without complex miter work. The 13/16 inch width and matched dark bronze color give you predictable coverage and a unified look wherever channel trim changes direction on cabinets or fixtures. For projects using dark bronze aluminum L-channels from Wurth Baer Supply, this connector provides the defined corner geometry that keeps trim lines consistent across the entire installation.