diff --git a/examples/tiles/penrose_basket.scad b/examples/tiles/penrose_basket.scad
index 3ca40275..719d8162 100644
--- a/examples/tiles/penrose_basket.scad
+++ b/examples/tiles/penrose_basket.scad
@@ -10,13 +10,12 @@ basket_radius = 40;
 radius_in_plane = basket_radius / 1.25 / cos(36);
 n = 4;
 line_diameter = 2;
-shell = "YES";
-shell_random_threshold = 0.5;
+shell_random_threshold = 0.5; // 0 ~ 1
 $fn = 4;
 		
-penrose_basket(basket_radius, radius_in_plane, n, line_diameter, shell, shell_random_threshold);
+penrose_basket(basket_radius, radius_in_plane, n, line_diameter, shell_random_threshold);
 
-module penrose_basket(basket_radius, radius_in_plane, n, line_diameter, shell, shell_random_threshold) {
+module penrose_basket(basket_radius, radius_in_plane, n, line_diameter, shell_random_threshold) {
 	tris = tile_penrose3(n);
 
 	for(t = tris) {
@@ -28,7 +27,7 @@ module penrose_basket(basket_radius, radius_in_plane, n, line_diameter, shell, s
 				line_diameter
 			);
 
-			if(shell == "YES" && rands(0, 1, 1)[0] < shell_random_threshold) {
+			if(rands(0, 1, 1)[0] < shell_random_threshold) {
 				inward_ratio = (basket_radius - 0.25 * line_diameter) / basket_radius;
 				outward_ratio = (basket_radius + 0.25 * line_diameter) / basket_radius;