Small engine air filters paper briggs and stratton carded Replaces B&S No.491588. Fits 4-6 H.P. Vertical Shaft engines & 3 & 5 H.P. Horizontal Shaft engines. Quantum series Nos.121700 & 122700, 124700. Size: 5- 1/4 inches L x 4- 1/2 inches W x 1 inch H.