Do you want to plugin your dry machine 10-30 plug and A/C 6-20 (or 6-15)plug to a 10-30 power inlet?
It can help you get a extra 6-20 or 6-15 power inlet to plugin dryer 10-30 power inlet.
Of course, your dryer still can work in the same time.
It is more easy to use than a regular 10-30P to 6-20R adapter cord avoid plugin and pullout frequently.
Please refer the "Parkworld #60066"
Perhaps this is hard to find on market.