18" Bars are made with a 7" Bird.
36" and 42" Bars are made with a 9" Bird.
Unrigged Spreader Bar
For reference, most of our bars are made on .096" diameter bars, including all floating squid and machine bars. We recommend .096" diameter bars unless you are making a bar with a large number of teasers or the teasers have a lot of water drag.