Both end fittings are AN - (Dash) 3 female. AN fittings are highly popular in motorsport but problem is production cars rarely if ever use AN fittings due to cost. Nissan uses a metric M10 X 1.0 thread pitch fitting on the brake line end on the N16 where the brake hose is supposed to be bolted to it. To get around this issue Fastbrakes supplies adapters as pictured below.
The silver coloured adapter is a metric M10 X 1.00 female to male AN -3 adapter. The gold coloured adapter is a 90 degree "L" shaped male AN -3 to male NPT 1/8 27 adapter. Wilwood specifies an 1/8 27 NPT inlet fitting for its SL6R caliper. Picture below shows both adapters bolted to the brake hose.
The end in red frame bolts to the brake line on the Slowtra. The end in blue frame bolts to the Wilwood caliper. Everything is perfectly usable except for one issue. Increasing the number of adapters increases the number of failure points for leaks to happen. As brake hoses metric end fittings are widely available I'm not sure why Fastbrakes is supplying an additional adapter. On top of this Fastbrakes further supplied an alternative longer L shaped adapter as pictured below.
I am now looking to have a new brake hose fabricated with AN - 3 male end fittings at one end and metric M10 X 1.00 pitch female end fittings for the other end. Also thinking of replacing the steel "L" shape male AN -3 to male NPT 1/8 27 adapter with one of this bling aluminium blue anodize adapters from either Earls or Goodridge.