ORFS braze tube sleeves is according to SAE J1453 or ISO 8484-3, there are two types of braze sleeves as follow:
For formed tube connections: Braze sleeve [BRSL-A (standard) and BRSL-B (option)]
ORFS_braze_Metic_inch_tubing_sleeves_size_Chart
Braze-on reducing sleeve (BRRDSLA [standard] and BRRDSLB [optional])
