A: Hello and thank you for your question! While we are currently in the process of updating our sizing charts with our new Jumbo and Jumbo Plus dimensions, here are our most up-to-date dimensions: Small - 20" x 15" x 3" Medium - 30" x 20" x 3" Large - 36" x 27" x 3" Jumbo - 40" x 32" x 4" Jumbo Plus - 53" x 40" x 5" These dimensions will provide a better point of reference for back seat compatibility.