Kunde:
<TelerikAutoComplete Data="@DataCustomer" TItem="@Customer" ValueChanged="@((string value) => OnComboCustomerValueChanged(value))">
    <ItemTemplate>
        @(nameof(Customer.customerName))
    </ItemTemplate>
    <FooterTemplate>
        <h6>Anzahl: @DataCustomer.Count()</h6>
    </FooterTemplate>
    <NoDataTemplate>
        <div class="no-data-template">
            <TelerikSvgIcon Icon="@SvgIcon.FilesError" Size="@ThemeConstants.SvgIcon.Size.Large"></TelerikSvgIcon>
            <p>No items available</p>
        </div>
    </NoDataTemplate>
</TelerikAutoComplete>

protected override async Task OnInitializedAsync()
{
    List<Customer> customers = new List<Customer>();
    customers.Add(new Customer()
        {
            customerId = "",
            customerName = ""
        });

    DataCustomer = customers;
}

 private void OnComboCustomerValueChanged(string value)
 {
     ComboCustomerValue = value;

     if (value != null && value.Length > 3)
     {
         if (DataCustomer == null)
         {
             List<Customer> Data = new List<Customer>();
         }

         if (DataCustomer.FirstOrDefault(item => item.customerId == value.ToString()) == null)
         {
             IO.Swagger.Api.CustomerApi customerApi = new IO.Swagger.Api.CustomerApi("https://server:8080");
             foreach (var itemsFound in customerApi.ApiV1CustomerIdGet(Convert.ToInt32(value)))
             {
                 if (DataCustomer.FirstOrDefault(item => item.customerId == itemsFound.Id.ToString()) == null)
                 {
                     DataCustomer.Add(new Customer()
                         {
                             customerId = itemsFound.Id.ToString(),
                             customerName = itemsFound.Name + @" (" + itemsFound.Id.ToString() + @")"
                         });
                 }
             }

         }
     }
 }

<TelerikGrid class="NewPairsGrid" 
            Data="@Pairs" 
            AutoGenerateColumns="false"       
            RowHeight="15" 
            Height="1000px" 
            Pageable="true"
            PageSize="25"
            
><GridColumns><GridColumn Title="Pair Info" width="200px"><Template Context="dataItem"><div>
                @DisplayTokenImage(dataItem as EthPairTradeInfoVDto)
                @($"{(dataItem as EthPairTradeInfoVDto).TokenSymbol} / {(dataItem as EthPairTradeInfoVDto).LpTokenSymbol} - {(dataItem as EthPairTradeInfoVDto).TokenName}")
            </div></Template></GridColumn><GridColumn Title="Total Price ETH" width="150px"><Template Context="dataItem"><div>
                @FormatPrice(dataItem as EthPairTradeInfoVDto)
            </div><div>
                @if (dataItem is EthPairTradeInfoVDto ethPairTradeInfoVDto)
                {
                    var UsdPrice = ethPairTradeInfoVDto.CurrentPriceUsd.GetValueOrDefault();
                    @if (UsdPrice > 0)
                    {
                        @($"${UsdPrice} USD")
                        ;
                    }
                    else
                    {
                        @("Looking for USD Price.../")
                        ;
                    }
                }
            </div></Template></GridColumn><GridColumn Field="PairCreatedTimeStamp" Title="Token Age" width="75px"><Template Context="dataItem">
            @if (IsLessThanHour(dataItem as EthPairTradeInfoVDto))
            {
                <i class="fas fa-leaf"></i>
            }
            @if (dataItem is EthPairTradeInfoVDto ethPairTradeInfoVDto)
            {
                var timestamp = CalculateElapsedTime(dataItem as EthPairTradeInfoVDto);
                <span class="tooltip-target">@timestamp</span><TelerikTooltip TargetSelector=".tooltip-target" Width="250px" Height="150px" Position="@TooltipPosition.Right"><Template Context="ttipContext"><span>
                            Timestamp: @(ttipContext.DataAttributes)
                        </span></Template></TelerikTooltip>
            }                     
            @* @CalculateElapsedTime(dataItem as EthPairTradeInfoVDto) *@
        </Template></GridColumn></GridColumns></TelerikGrid>