C.R. LAURENCE FS261 CRL Window Channel Balance Guide Rivet - 100/Pk. CRL Balance Guide Rivets are aluminum, 5/8 by 3/32 inch (15.9 by 2.4 millimeter) hollow-tip rivets used to install top and bottom guides to window balance channels. The H3740 installation tool is recommended for use when setting the rivet with the guide and channel. These rivets are also available in a bulk package containing 1000 rivets.. Part Numbers Variations: FS261