RE: IS this model good to convert?
Converting the U99 would be a challenge. This model is about 1.5 ft in length, about 2 inches wide. You would have to install nano-sized radio equipment. Someone at Subpirates tried converting this model but so far no news. If you want a U-boat model I'd recommend the Revell 1/72 Type VIIc or VIIc/41.