K&N Filters RG-1001RD - Universal Chrome FilterUniversal clamp on air filter featuring a washable, red oiled cotton gauze media. Engineered to increase horsepower and acceleration, its conical design and durable rubber flange allow for secure installation across a wide range of custom automotive and racing applications Round tapered (conical) with a metal chrome top 4 in (102 mm) inside diameter with rubber inserts for 3. 5" and 3" Inlet sizes 5. 5 in (140 mm) height, 6 in (152 mm) base outside