I would just get a #6 rubber Bung for 1 galln sized and 3 liter sized jugs.
<table ="Catalog" id="products" align="center" border="1" bordercolor="#000000" cellpadding="2" cellspacing="0" width="100%"><t><tr><td ="table" align="default" width="2%"><div align="center">
4612 </td>
<td width="5%"><div align="center">
</td>
<td width="20%">
Gum Stopper #6 Drilled Rubber
Sizing Chart located on our Resource page.</td>
<td width="2%"><div align="right">$0.99</td>
<td width="2%">
</td></tr></t></table>You can also get #2 or #3 sized bungs to fit standard sized wine bottles for the extra for topping off later.
<table ="Catalog" id="products" align="center" border="1" bordercolor="#000000" cellpadding="2" cellspacing="0" width="100%"><t><tr><td ="table" align="default" width="2%"><div align="center">
4608 </td>
<td width="5%"><div align="center">
</td>
<td width="20%">
Gum Stopper #2 Drilled Rubber
Sizing Chart located on our Resource page.</td>
<td width="2%"><div align="right">$0.59</td></tr></t></table>
<table ="Catalog" id="products" align="center" border="1" bordercolor="#000000" cellpadding="2" cellspacing="0" width="100%"><t><tr><td ="table" align="default" width="2%"><div align="center">
5102 </td>
<td width="5%"><div align="center">
</td>
<td width="20%">
Gum Stopper #3 Drilled Rubber
Sizing Chart located on our Resource page.</td>
<td width="2%"><div align="right">$0.89</td></tr></t></table>