They use a lot of batteries. Whilst the volume of batteries may differ depending on the dimensions of the custom made shade, my 27-by-73-inch shade needed a comically substantial number—8 D batteries, for an added $17. Lutron notes in its FAQ that battery longevity is variable, according to use, but https://www.google.com/maps/place/Design+Blind+And+Drapery+Service,+Inc/@27.181062,-80.24557,15z/data=!4m6!3m5!1s0x88dedd13c6303339:0x7e9557fd3e2b0c9f!8m2!3d27.181062!4d-80.24557!16s%2Fg%2F1tp08ynf?hl=en-US&entry=ttu&g_ep=EgoyMDI1MDMxMS4wIKXMDSoJLDEwMjExNDU1SAFQAw%3D%3D