MVC5 + dropdownlist selectitems issue

Hi,

I would like to fill the dropdownboxFor list items in the view from a string with values, stored in one field from the model. Hope this makes sense.

The model of the view

@model  IList<SeaFuy.Models.tblArticleSpecDefinition>

I have a view 

@using SeaFuy.Library
@model  IList<SeaFuy.Models.tblArticleSpecDefinition>
@{
    ViewBag.Title = "ManageFlexValues";
    Layout = "~/Views/Shared/_Layout.cshtml";
}<main class="products">
    @using (Html.BeginForm())
    {<fieldset><ul id="tabs"><li><a href="#details" id="details-tab">Details</a></li></ul><div class="tabContent" id="details"><div class="col-max-width"><div class="data-group">
                        @for (var i = 0; i < Model.Count; i++)
                        {<div class="display-none">@Html.EditorFor(x => x[i].SP_ID)</div>
                            if (Model[i].SP_TYPE == "C")
                            {<div class="list-left">@Html.DisplayFor(x => x[i].SP_DESCRIPTION)</div><div class="list-right"> @Html.DropDownListFor(x => x[i].SP_SV_VALUETOSTORE, new SelectList(new List<string>() { "ss", "bb" })) </div>
                            }
                            else
                            {<div class="list-left"> @Html.DisplayFor(x => x[i].SP_DESCRIPTION)</div><div class="list-right">@Html.EditorFor(x => x[i].SP_SV_VALUETOSTORE) </div>
                            }
                        }</div></div></div></fieldset><div class="button-container flexbox"><input class="new" type="submit" value=@SeaFuy.ResourceProviders.LocalizationResourceProvider.Current.GetString("stAanmaken") /></div>
    }</main>

you see that the values of the dropdownlist are now "ss" and "bb". These values should be replace with the list of strings in the field 

x[i].SP_VALUETYPE

So the Model of the view is a list of records, Depening on one field in a record it show a textbox or a dropdown. The values of this dropdown should come from another field in the same record.But somehow i cannot get this to work. I thought i make viewbags, but the problem is that this is a list. So i do not know how many records the user wil enter.

Any suggestions how to tackle this.

tnx. Marcel