2x3 these endcaps are designed for the 2x3 in. Vinyl downspouts found is most hardware stores in canada and the us.
You can create your own hydroponics grow system at home with a small start up cost. There are many downspout tutorials on youtube to follow and you will need more than just these endcaps.
These endcaps slot on the end and you can design your own configuration depending on how many channels you want. The endcaps with the 1/2 pvc pipe adapter works better than the bottom bulkheads because they don't get choked out by the root system near as fast. The caps were designed by me for tight tolerance on the downspout they are a little hard to get on but they will fit. Step 1: cut your downspout into the length you would like for your system. They come in 10 ft sections so most people with the room either keep them 10ft or in half to make 5ft sections.Step 2: dry fit all pieces together in the configuration you want before glueing. Step 3: apply a bead of silicone around the end of the downspout and fit your end cap to it do not use tools to force it you should be able to get it on with just your own hands.
The best way to to get one corner in first and work your way around without binding it to much. Same process for the 1/2 pvc adapter endcaps. Apply silicone to the 1/2 pipe and let dry.
Step 4: let the silicone dry for 24 hours before introducing water. Make sure you're ordering the correct size for your downspout, i sell 2x3 and 3x4 i'm not responsible for you ordering the wrong size for your application. Vinyl downspout and the silicon not included. This item is made of pla.