diff --git a/docs/lib-polysections.md b/docs/lib-polysections.md
index f9197965..351d8936 100644
--- a/docs/lib-polysections.md
+++ b/docs/lib-polysections.md
@@ -14,26 +14,14 @@ You can also view it as a better polyline3d module if you want. If you have only
 
 When using this module, you should use points to represent each cross-section. 
 
-You need to provide indexes of triangles, too. This module provides three prepared triangles indexes. One is `"RADIAL"`. For example, if you have a cross-section such as:
-
-![polysections](images/lib-polysections-3.JPG)
-
-When using `"RADIAL"` (default), the module will cut them into triangles from the first point to each remaining point:
-
-![polysections](images/lib-polysections-4.JPG)
-
-If your cross-sections are hollow, you may use `"HOLLOW"`. For example:
+If your 2D shape is not solid, indexes of triangles are required. This module has a built-in index vector suitable for one type of hollow shapes. For example, if you have a cross-section such as:
 
 ![polysections](images/lib-polysections-5.JPG)
 
-When using `"HOLLOW"`, the above shape will be cut into triangles such as:
+When `triangles` is `"HOLLOW"`, the above shape will be cut into triangles such as:
 
 ![polysections](images/lib-polysections-6.JPG)
 
-When using `"TAPE"`, a tape shape will be cut into triangles such as:
-
-![polysections](images/lib-polysections-10.JPG)
-
 You can cut triangles by yourself, for example, the indexes of the above triangles is:
 
     [
@@ -50,7 +38,7 @@ Triangles may be defined in any order.
 ## Parameters
 
 - `sections` : A list of cross-sections. Each cross-section is represented by a list of points. See the example below.
-- `triangles` : `"RADIAL"` (default), `"HOLLOW"`, `"TAPE"` or user-defined indexes. See example below.
+- `triangles` : `"SOLID"` (default), `"HOLLOW"`,  or user-defined indexes. See example below.
 
 ## Examples
 
diff --git a/src/polysections.scad b/src/polysections.scad
index 265e274a..949d1e62 100644
--- a/src/polysections.scad
+++ b/src/polysections.scad
@@ -11,10 +11,9 @@
 *
 **/
 
-include <__private__/__triangles_radial.scad>;
 include <__private__/__triangles_tape.scad>; 
 
-module polysections(sections, triangles) {
+module polysections(sections, triangles = "SOLID") {
     module solid_sections() {
         leng_sections = len(sections);
         leng_pts_section = len(sections[0]);
@@ -80,12 +79,8 @@ module polysections(sections, triangles) {
                 )
             ) idxes; 
 
-        function tris() = triangles == "RADIAL" ? __triangles_radial(sections[0]) : 
-            (
-                triangles == "HOLLOW" ? hollow_tris() : (
-                    triangles == "TAPE" ? __triangles_tape(sections[0]) : triangles 
-                )
-            );
+        function tris() =
+            triangles == "HOLLOW" ? hollow_tris() : triangles;
 
         module two_sections(section1, section2) {
             for(idx = tris()) {
@@ -114,7 +109,7 @@ module polysections(sections, triangles) {
     }
     
     //
-    if(triangles == undef) {
+    if(triangles == "SOLID") {
         solid_sections();
     } else {
         triangles_defined_sections();