C.R. LAURENCE FS101B CRL Window Channel Balance Top Guides - Bulk 50/Pk. At times you will find that a particular Window Channel Balance is very popular in your area or you may have a large job. Make sure you always have the correct guides on hand by ordering a package of CRL Window Channel Balance Top Guides in a bulk pack of 50. With this CRL Window Channel Balance Top Guide, the most commonly used bottom guide is the FS153B..