1/4" x 4" x 6" Universal Aluminum Plates 1.75" mast to 1" boom  or 1.75" boom to 1" yagi element or for GP/ Vertical Antenna project 1.75" mast to 1" insulated vertical element. With 4 yellow zinc plated U-bolts and saddles just for 1.75" u-bolts. U-Bolts:This is professional grade series. This series provides high strength steel 5/16” U-bolt with a patented ribbed and notched 13 gauge double edge saddle and hex nuts. This unique clamp offers a lightweight alternative with outstanding strength and seal-ability. Mast Plates keep your Yagi stable and properly secured on the mast. 

from 7/15/21. 
2" is available...