This is a used item, but I believe it is in good condition. Please understand this before purchasing. "The number one modification you've always wanted to try!" "This is it for resistor removal! The number one modification!" "The number one modification to show off to your friends!" A fascinating modification that you've always dreamed of, believing it will surely make you faster... "Floating the counter gear" The difficulty of processing these methods to center the gear is, like the "Roller 520 Dig," you probably understand that drilling a hole in the center is quite difficult. Insert the gear dig into the counter gear hole, and then dig in to easily create a φ8mm hole. Regarding the dimensions, we measured the old and current 830, and although it will be an interference fit, we made the diameter on the gear side so that it is neither too tight nor too loose. Chuck diameter: Φ3mm (3mm collet chuck recommended) 【Notes】 ・This is a jig shape to make it easier to achieve accuracy. Please understand that it is not 100% guaranteed. ・Work can be done manually or with the jig alone, but it requires a fair amount of force. Please be careful not to get injured. ・You can also use electric tools such as lathes, drill presses, and milling machines. ・This is a jig for expanding the hole for inserting the counter gear bearing. Please be careful when using it for anything else. ・It is made based on Tamiya gears. We do not recommend using it on aluminum or carbon gears due to their material properties, and we are not responsible for any disadvantages incurred by customers when using it on those materials. ・Returns and exchanges are not accepted except for product defects such as chips and distortions. ・Please note that we are not responsible for any damage caused by using the jig.