I have decided to purchase a Trend 3" diamond card to sharpen my carbide wood router bits and have been very happy with the results so far. I am a little concerned that the grit on the card will wear off a bit I expected but understand that this is considered "normal" and will not affect sharpness in any way.Time will tell but it should be noted that the trend card comes with a 5 year guarantee At this point I would certainly recommend the trend card for the cheaper and (perhaps) less durable card.