KT is their designation for a pipe size that matches the OD of chain link top rail 
This is the one that has three pipes meeting. Two ends and one pass thru - good for framing in gable vents/fans. Extra holes to pin the pipes to prevent linear movement, aka run a screw in to keep and from pulling out and prevent clamp from sliding on thru pipe. 
This is the bypass cross - good for my lengthwise truss ties going end to end. No holes but I'll run a screw in each pipe for good measure. 
All are better designs than what I can get from a high tunnel supplier and for a decent price($8 instead of $4). I can't think of anywhere I could have used them already because the trusses are all weird angles - no 90 degree angles. End walls with gable vents and the truss ties can use these though.
I had already not been looking forward to using the flat bar straps for the last of the framing. "Everything's 90 degrees. Someone's gotta make what I need" he grumbled.
This is what the 90 degree cross clamps look like. 
This is what I used for the odd angle Tee connections. End cap with tab bolts into strap. Works for any angle.
Wednesday: Mostly cloudy, with a high near 66. Calm wind.
Borrowed a ladder from the neighbor that I'll strap down to the roof of the SUV every which way I can. Poly and wiggle wire/track are here. ---------------
Need two verticals inside the pentagon like shape for the gable vents. Add two horizontal cross bars in between the verticals with the connectors that make the pipes flush with each other. 
I can see the -- end of the tunnel