1,Desktop optical metal trackball with 38mm diameter 2,Water/dust-proof,meets IP65 ... 3,With click buttons and palm-rest Key Features- Optical metal trackball(dia:38mm),made of abrasion-resistant stainless steel- Specially ... 106.00 mm x 46.50 (LxWxH) IP65 Desktop Optical Metal Trackball mouse with 38mm doa,eter