The salts in 20x solution are at a very high concentration. It has been found that at temperatures below 44 degrees F (6 degrees C), the salts fall out of solution. If this occurs during your shipment conditions, please stir the product to get the salts back into solution.
TBS is a solution of Tris Buffered Saline for use with immunolabeling techniques as a wash buffer.
Tween 20 is sometimes added to promote more effective washings, resulting in decreased non-specific background staining. Tween 20 is also known to promote reagent spreading in automated staining methodologies.