How can I restrict to buy more than one unit of one item of the cart

Hello... I would like to know if it´s possible to restrict users to buy only one unit of a specific item of the cart ... even if they try to modify the quantity of that item in the cart.
Actually, the "Add to Cart" button is restricted to add only one unit of each product to the cart, but in the cart clients are allowed to modify quantities of all items.
I would like to restrict them modify or buy more than one unit of a specific item using some of the rulles built in the cart...

Can you help me clarify how to do it please??

You can remove the quantity update option from the cart.

Thanks Ray... Is it possible to remove the quantity update option for a special item in the cart?? I would not like to remove it for all items in the cart.

Can I use a eCart rule to do it?

You can't do it with an eCart rule, but you can put a simple IF statement around the update field to check for the ID of the item and not show it if you don't want quantity update to be possible.

Got it thanks... I´m not a coder but I will try do do it...

Thanks from Chile