The marble shift knob is our regular product, so we can send you some free samples if you need to check our quality. You only need to bear the shipping cost. It’s only a tiny parcel and will not cost too much.
The marble shift knob can pass most tests, such as CE, RoHS, CA Prop 65. For some tests, even we didn’t do it, but the product can pass it.
As a factory since 2002, we can have some cases for your reference and hope they can do some help.
(1) Some customers know their thread standard, so we only need to send them one adapter. In this way, customers can save some costs.