The versatility of Parker's t-slot aluminum framing systems makes them ideal solutions for machine bases and frames, linear slide systems, safety guarding and enclosures, worktables, and structural framing, as well as for use in materials handling systems. Their components include extrusion profiles, fasteners, panels, doors, brackets, gussets and plates. When using our custom T-slotted aluminum extrusions, you simply insert a T-nut and fastener into the extrusion and tighten it to create a durable, strong and lightweight structure that is both functional and attractive. A T slot is one 20 amp circuit for two plugs, or 10 amps per plug. A split is 30 amps for two plugs, or 15 amps per plug. T slots were a lowering of standards. I didnt know either so i had to research. 20A Outlets: Some electrical outlets have a 'T' shaped slot on the neutral instead of just a vertical slot. These outlets are rated for 20A, and can receive special plugs (with a sideways neutral prong) for appliances which draw more than 15A.