I am so sorry for the standoff installation problem. It is a stupid mistake, each NGH38 must be tested before shipping. but standoff parts are separated packing, workers packed a big-head M5*40 screws and wrong. I had not paid enough attentions while I am moving factory from North to South China. 

It is a really stupid work and shame, please forgive my mistake.

Now, please try to use these method to install it.

a. if possible, better is with beam mounting.

b. try to find  small-head M5*40 screws.

NGH will never escape and make solutions.

Sorry again

michael