I have installed a 3d printed thumb throttle attachment fron Etsy on my City5 and it works OK. I saw this thumb throttle replacement for the twist throttle on ebay and want to ask if anybody has tried it. Here is a link to the thumb throttle.
https://www.ebay.com/itm/114158460232?hash=item1a945fdd48:g:aBIAAOSwCg9eenbX&amdata=enc%3AAQAHAAAA8OpGROewaXPB3ObulWCA7K2l4MLdA%2BTlu5KOMAQ3Tk72hntrwcryREHy%2Bki6IgVFu4pBt%2F7LbqTNDLkw0dHfAdokrKNYDl5Unvde7gbMCkgXvkY2pVmA%2FV3PLKcaK0wf58RwFN9rGK25IfppP1R92DuMkC4l01c0VJqWyhtfOK7fWICj1kxHNNd48Vjv9imXb5pzryUsIA677APcpuV95IP5szXNjqEODg7rFXkHDEUN7y9EebE6ykDi65at3Xj0SU%2FPIM2PmSN3Vud%2BnVwDAzrAvVMsj3mH0QY0jy4amp8hPpR%2FoXhtiEk0nGr3bzmbIA%3D%3D%7Ctkp%3ABFBM_JfWp8Zg
That link is to a dedicated thumb throttle not a 3d printed? I have the set off ebay. Works fine. Comes with a key fob and battery covers. I like it. The thumb button slightly gets in the way and keeps you from grabbing the whole grip when your not using it but, you can?t have both. I think the covers could be improved if they had a loop molded in to thread a cord or strip of velcro through to hold them on or tie it to keep them from getting lost. Otherwise it?s a decent kit for the money. :)
I have one got from Amazon link below for my RR6+, works great, takes up less space than the twist and allows you to use standard grips both left and right, so no more 3/4 grip.
https://amzn.to/3UsLO37