So I'm assembling a pull up bar and its assmebly instructions look like this

[![enter image description here](https://i.stack.imgur.com/xCebY.jpg)](https://i.stack.imgur.com/xCebY.jpg)

In the parts list it mentions only one type of spring washer (quantity 4). 

But it actually came with two types of washers (quantity 4 **each**), [type1](https://en.wikipedia.org/wiki/File:Plain_washer1.jpg) and [type2](https://en.wikipedia.org/wiki/File:Grower01.jpg).

Am I supposed to use both of them? And in what way? Any help would be appreciated!