diff --git a/src/style_manager/model/Layers.js b/src/style_manager/model/Layers.ts
similarity index 53%
rename from src/style_manager/model/Layers.js
rename to src/style_manager/model/Layers.ts
index 952e1589b..71e81bde3 100644
--- a/src/style_manager/model/Layers.js
+++ b/src/style_manager/model/Layers.ts
@@ -1,8 +1,10 @@
 import { Collection } from '../../common';
 import Layer from './Layer';
 
-export default class Layers extends Collection {
-  initialize(p, opts = {}) {
+export default class Layers extends Collection<Layer> {
+  prop: any;
+
+  initialize(p: any, opts: { prop?: any } = {}) {
     this.prop = opts.prop;
   }
 }