A rachet involves a round gear or a linear rack with tooth, and a pivoting, spring-loaded finger named a pawl that engages the teeth. The teeth happen to be uniform but Ratchets Wheel asymmetrical, with each tooth having a moderate slope using one edge and a much steeper slope on the various other edge.
When the teeth are relocating the unrestricted (i.e. forward) course, the pawl easily slides up and over the carefully sloped edges of one’s teeth, with a planting season forcing it (often with an audible ‘just click’) into the depression between your teeth as it passes the tip of each tooth. When the teeth move in the contrary (backward) direction, even so, the pawl will catch against the steeply sloped edge of the 1st tooth it encounters, thus locking it against the tooth and stopping any further motion in that direction.
Backlash
Because the ratchet can only stop backward movement at discrete items (i.e., at tooth boundaries), a ratchet does let a limited amount of backward movement. This backward motion-which is limited to a maximum distance add up to the spacing between your teeth-is called backlash. Where backlash must be minimized, a smooth, toothless ratchet with a high friction surface such as rubber is sometimes employed. The pawl bears against the surface at an angle so that any backward movement will cause the pawl to jam against the top and therefore prevent any further backward motion. Since the backward travel distance is mainly a function of the compressibility of the high 
friction surface, this system can bring about significantly reduced backlash.
This Ever-power 54t Ratchet kit works as a direct replacement and is super easy to install. Just remove the freehub body the parts you find here will maintain there, grease up the new parts and re-assemble the hub. Boom! You’ve just considerably increased the engagement factors on your hub. To give you a better idea of how this boosts your ride think of the engagements in degrees of a circle, with the 18t you need to approach the cassette 20 degrees to reach another engagement and with the 54t that knocks it right down to 6.66 degrees! That’s less than a 3rd the length it needs to move to hit another tooth! You may be wondering if you can really see the difference. Just pedal your bike around and keep the bike moving by using tiny pedal strokes and back-pedaling. You’ll see there’s going to end up being lot’s of slop between engagements. Visualize if that “slop” was decrease to a third! I’m sure imaginable that’s a huge upgrade. Therefore, if you weren’t already entirely convinced on the 54t ratchet system I hope this can be the turning indicate getting one!