If you want to sell a specific item regardless of the available quantity, then mark it as Replenishable There is a replenishable check-box on the Product General page. 
When updating various channels, SellerCloud sends a fixed quantity for the replenishable products so that it consistently shows a specific available quantity. 
For eBay, it will look at the value in the "Fixed Price Quantity" field. For Amazon, use the Fixed Quantity setting on the Amazon Properties page.
On some channel properties pages, you may need to check a box to reveal the default qty field.
When set to Replenishable, the Safety Quantity is ignored.

These fields can be updated in bulk. Please refer to the bulk update column page for the correct column header.

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