Use these to test extrusion accuracy and thread width.
In Slic3r, you should set "detect thin wall" to on.
In kisslicer, there appears to be gaps, depending on style settings.
For the 0.4 model, the following Style profile in kisslicer produces unexplained gaps:
layer_thickness_mm = 0.1
extrusion_width_mm = 0.35
num_loops = 5
skin_thickness_mm = 0.8
infill_extrusion_width = 0.5
infill_density_denominator = 10
stacked_layers = 1
use_destring = 1
use_wipe = 1
loops_insideout = 0
infill_st_oct_rnd = 1
inset_surface_xy_mm = 0.175
seam_jitter_degrees = 0
seam_depth_scaler = 1

While the following Style profile in kisslicer does not produce gaps:
layer_thickness_mm = 0.25
extrusion_width_mm = 0.5
num_loops = 3
skin_thickness_mm = 0.8
infill_extrusion_width = 0.5
infill_density_denominator = 4
stacked_layers = 1
use_destring = 1
use_wipe = 1
loops_insideout = 0
infill_st_oct_rnd = 1
inset_surface_xy_mm = 0
seam_jitter_degrees = 0
seam_depth_scaler = 1