| Product attributes | Parameter |
| Mounting hole position | Precisely align |
| Air tightness testing | No leakage detected under negative pressure of 0.1 MPa |
| Appearance Ⅰ | There is no supplier logo on the surface |
| Appearance Ⅱ | There are no appearance defects such as dirt, rust, paint peeling, etc |
| Assembly rotation | It rotates flexibly by hand, without any clamping stagnation or abnormal noise |