Vforce 4Ri Reed Valve Block Yamaha YZ 85 02-23 24 25 V Force4R Carbon Reeds MX

(The unique design of the VForce reed valve system features double the reed tip surface over a conventional reed valve design. 2) Because the reed petals only need to travel half the distance of that on a conventional reed valve design, there is a greater chance of them being fully opened as well as a better chance of sealing when they are "closed".

eBay