Source Double slotted aluminium H upright channel on m.alibaba.com
8020, 1010, 10 Series 1 Inch x 1 Inch T-Slotted Aluminum Extrusion DIY Extruded Linear Slot Bar Rail 80/20 (12" Long, Black Anodize): Amazon.com: Industrial & Scientific
What is T-Slot Aluminum Framing? How do You Use It?
8020, 3075, 15 Series 3" x 0.75" Aluminum Smooth T-Slot Extrusion x 36" Long T Slotted Extruded 80/20 Profile - Shelving Hardware - Amazon.com
1.5" X 1.5" Mono Slot T-Slotted Aluminum Framing Extrusion - Alufab Inc.
T-Slot Aluminium Extrusion Profile
1.5" x 1.5" Lite Smooth T-Slotted Aluminum Extrusion – Faz-Store
8020, 1010, 10 Series 1 Inch x 1 Inch T-Slotted Aluminum Extrusion DIY Extruded Linear Slot Bar Rail 80/20 (36" Long, Smooth, Clear Anodize): Amazon.com: Industrial & Scientific