<apex:page standardController="Opportunity"  renderAs="pdf">

 
  <h1>Packing Slip</h1>
  
  <p></p>
  <h2>Ship To</h2>
     <p><b><apex:outputText value="{!Opportunity.Account.Name}"/></b>
     <br><apex:outputText value="{!Opportunity.ia_crm__Ship_to__r.FirstName}"/><apex:outputText value=" {!Opportunity.ia_crm__Ship_to__r.LastName}"/></br>
      <br><apex:outputText value="{!Opportunity.ia_crm__Ship_to__r.MailingStreet}"/></br>
      <br><apex:outputText value="{!Opportunity.ia_crm__Ship_to__r.MailingCity}"/><apex:outputText value=", {!Opportunity.ia_crm__Ship_to__r.MailingState}"/><apex:outputText value=" {!Opportunity.ia_crm__Ship_to__r.MailingPostalCode}"/></br>
      </p> 
     
    <p>PO #:<b><apex:outputText value=" {!Opportunity.Name}"/></b>
    <br>Order Date: <apex:outputText value=" {!Opportunity.CloseDate}"/></br>
    <br>Ship Date: <apex:outputText value=" {!TODAY()}"/></br></p>

<p></p>
<p></p>
<p></p>
<p></p>


<apex:pageBlock id="products_list">


      <apex:pageblockSection title="Shipment Details" columns="3">
      
          <apex:pageBlockTable value="{!opportunity.opportunityLineItems}"  var="prd" width="600px">

              <apex:column headerValue="Product" value="{!prd.ProductCode}"/>
              <apex:column headerValue="Description" value="{!prd.Product2.Name}"/>
              <apex:column headerValue="Quantity" value="{!prd.Quantity}"/>

        </apex:pageBlockTable>
    </apex:pageblockSection>
</apex:pageBlock>


</apex:page>

I have the Visualforce page above, which allows me to create a packing slip that can be printed out for some of our opportunities. However, we want the list of Opp Products to be limited to inventory only, and we want to filter out the non-inventor items from this view. 
How can I filter the apex:pageBlockTable to only include specific items?