Tailwheel base standard for the WHLT-11D (can be added to other units). This part is machined from aluminum extrusion. It is to be used with 1.75 wide flat springs at a 45 degree angle to the ground. This unit has one 5/16 inch attach bolt hole that can be opened to as much as 7/16. See the WHLTWBED for the two bolt attach version. The WHLTWBADT1.5 adapater allows fit to a 1.5 inch wide spring and the WHLTWBADT1.25 can be used additionally to reduce further to 1.25 wide.