Patio Umbrella Deck Rail Mount

Uses 3/8" mounting bolts to attach holder & spacer to deck rail, with additional #8 deck screws for securing the spacers. 

Upper mount requires 1x 5/16 bolt and wing nut to adjust clamping. 

Update: 

-after 1 year in service this has held up very well. It survived regular use in the summer, as well as being outside in a Canadian winter. Still holding strong. 

-Added an alternative for the base to remove the 2x4 support.