Double Bass Bow 1/2. Offers students a good alternative to inexpensive wood bows, since they are more durable and will not warp. Our standard Fiberglass bows feature a half-lined bow frog with metal under-slide and an imitation three-part button. The Fiberglass bows come in a satin black finish, have genuine unbleached white horsehair, and a leatherette grip. Bass Bows fall within a weight range of 125-135 grams. All Glasser Bows have a lifetime warranty.