Kwikee 379600 6" x 21" Glow-In-Dark Step Tread The control unit is designed to be replaced on the pre-IMGL step units that were manufactured from 1999 to 2005 Note: This is Kwikee Part Number 909506003/90951003 Designed to replace the control unit on pre-IMGL step units that were manufactured from 1999 to 2005 Kwikee Glow In The Dark Dual Stripe Step Tread Replacement Non-slip tread with both reflective and phosphorus stripes Features a luminescent system, which glows in the dark once it has been exposed to natural or artificial light Methods of excitations include incandescent, fluorescent and black lighting as well as direct or indirect sunlight Glows the brightest during the first 30 minutes after activation has ceased, and remains visible to the night (darkness) adapted eye for up to 10 hours; 6 inch Width x 21 inch Length