Select options CRL 20″ Window Channel Balance – 1930/40 or 19-3/4 $1.00 Product Code: fa1930/40 or 19-3/4 Product Description: requires one of several types of nylon guides to be riveted onto the top and bottom of the channel. Customers can either order channel balances with guides pre-attached at the factory, or can order guide kits, with rivets included, and mount the guides themselves. CRL also offers the handy Cat. No. H3740 Rivet Set Tool, which mushrooms the rivet, giving it a very strong set.