The best filter in the world can't do its job if there are leaks in the seal of the airbox. That's why Twin Air provides a complete line of products to ensure a leak-proof, fool-proof fit. Twin Air's Power Flow kit comes with a rigid, lightweight, billet aluminium cage that provides a tight seal to the airbox and replaces your flimsy plastic stock cage. Includes a Fire-resistant Twin Air Filter. POWERFLOW KIT 152222C FANTIC XXF250 21-24 XXF450 21-23 XXE250 21-24 XXE450 21-24 YAMAHA YZ250F 19-23 YZ450F 18-22 YZ250FX 20-24 YZ450FX 19-23 WR250F 20-24 WR450F 19-23