It's very hard to see from that listing's photos, but there is a darkness knob just underneath the black handles, itself also colored black. When you look at th

It's very hard to see from that listing's photos, but there is a darkness knob just underneath the black handles, itself also colored black. When you look at the device from underneath, it's pretty obvious to see it, but it's not visible in any of the photos from that specific listing. Here's a listing with the same T-20 designation that shows the knob: https://www.ebay.com/itm/305337386341?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20200818143230%26meid%3D8bc4c1e44018476396817df402b3201a%26pid%3D101224%26rk%3D2%26rkt%3D5%26sd%3D115950183748%26itm%3D305337386341%26pmt%3D1%26noa%3D1%26pg%3D4429486%26algv%3DDefaultOrganicWebV9BertRefreshRanker%26brand%3DBrand&_trksid=p4429486.c101224.m-1 https://www.ebay.com/itm/305337386341?_trkparms=amclksrc%3DI... And here's another listing with the T20 designation (T20A, this time, instead of B), which also has a decent shot of the knob: https://www.ebay.com/itm/116014045221?hash=item1b02f9d825:g:gIsAAOSwTr1lgKJz https://www.ebay.com/itm/116014045221?hash=item1b02f9d825:g:...