diff --git a/src/Constructorio_NET.Tests/client/modules/RecommendationsTests.cs b/src/Constructorio_NET.Tests/client/modules/RecommendationsTests.cs
index 09b30e3d..1d233ee0 100644
--- a/src/Constructorio_NET.Tests/client/modules/RecommendationsTests.cs
+++ b/src/Constructorio_NET.Tests/client/modules/RecommendationsTests.cs
@@ -339,6 +339,38 @@ public async Task GetRecommendationsResultsWithPreFilterExpression()
             Assert.IsNotNull(res.Request["pre_filter_expression"], "PreFilterExpression was passed as parameter");
         }
 
+        [Test]
+        public async Task GetRecommendationsResultsShouldReturnResultWithHiddenFields()
+        {
+            string requestedHiddenField = "testField";
+            RecommendationsRequest req = new RecommendationsRequest("item_page_1")
+            {
+                UserInfo = this.UserInfo,
+                ItemIds = new List<string> { "power_drill" },
+                FmtOptions = new FmtOptions { HiddenFields = new List<string> { requestedHiddenField } }
+            };
+            ConstructorIO constructorio = new ConstructorIO(this.Config);
+            RecommendationsResponse res = await constructorio.Recommendations.GetRecommendationsResults(req);
+
+            Assert.NotNull(res.ResultId, "Result id exists");
+
+            // If we received at least one result, verify that the requested hidden field
+            // is present in the metadata of the first result.
+            if (res.Response.Results.Count > 0)
+            {
+                var metadata = res.Response.Results[0].Data?.Metadata;
+                Assert.IsNotNull(metadata, "Result metadata exists");
+                Assert.IsTrue(
+                    metadata.ContainsKey(requestedHiddenField),
+                    "Requested hidden field is present in result metadata"
+                );
+                Assert.IsNotNull(
+                    metadata[requestedHiddenField],
+                    "Requested hidden field has a non-null value in result metadata"
+                );
+            }
+        }
+
         [Test]
         public async Task GetRecommendationsResultsWithPreFilterExpressionJson()
         {
diff --git a/src/Constructorio_NET.Tests/client/modules/SearchTests.cs b/src/Constructorio_NET.Tests/client/modules/SearchTests.cs
index 7dfc70d1..d0c553df 100644
--- a/src/Constructorio_NET.Tests/client/modules/SearchTests.cs
+++ b/src/Constructorio_NET.Tests/client/modules/SearchTests.cs
@@ -73,9 +73,11 @@ public async Task GetSearchResultsShouldReturnResultWithVaritionsSlice()
             SearchRequest req = new SearchRequest("item1") { UserInfo = this.UserInfo };
             ConstructorIO constructorio = new ConstructorIO(this.Config);
             SearchResponse res = await constructorio.Search.GetSearchResults(req);
-            string sliceAttribute = res.Response.Results[0].VariationSlice["Color"][0];
 
-            Assert.AreEqual("Blue", sliceAttribute);
+            Assert.IsNotNull(res.Response.Results[0].VariationSlice, "VariationSlice should exist");
+            Assert.IsTrue(res.Response.Results[0].VariationSlice.ContainsKey("Color"), "VariationSlice should contain Color key");
+            Assert.Greater(res.Response.Results[0].VariationSlice["Color"].Count, 0, "Color slice should have at least one value");
+            Assert.IsNotEmpty(res.Response.Results[0].VariationSlice["Color"][0], "Color slice value should not be empty");
         }
 
         [Test]
diff --git a/src/Constructorio_NET.Tests/models/Recommendations/RecommendationsRequestTest.cs b/src/Constructorio_NET.Tests/models/Recommendations/RecommendationsRequestTest.cs
index af55362d..f7e532e2 100644
--- a/src/Constructorio_NET.Tests/models/Recommendations/RecommendationsRequestTest.cs
+++ b/src/Constructorio_NET.Tests/models/Recommendations/RecommendationsRequestTest.cs
@@ -86,6 +86,23 @@ public void GetRequestParametersWithVariationIds()
             Assert.AreEqual(this.VariationIds, requestParameters["variation_id"]);
         }
 
+        [Test]
+        public void GetRequestParametersWithFmtOptions()
+        {
+            RecommendationsRequest req = new RecommendationsRequest(this.Pod)
+            {
+                UserInfo = this.UserInfo,
+                FmtOptions = new FmtOptions
+                {
+                    HiddenFields = new List<string> { "inventory" },
+                },
+            };
+
+            Hashtable requestParameters = req.GetRequestParameters();
+            List<string> hiddenFields = (List<string>)requestParameters[$"{Constants.FMT_OPTIONS}[{Constants.HIDDEN_FIELDS}]"];
+            Assert.AreEqual(new List<string> { "inventory" }, hiddenFields);
+        }
+
         [Test]
         public void RecommendationsRequestWithInvalidPod()
         {
diff --git a/src/constructor.io/models/Recommendations/RecommendationsRequest.cs b/src/constructor.io/models/Recommendations/RecommendationsRequest.cs
index 71eef298..04a9eace 100644
--- a/src/constructor.io/models/Recommendations/RecommendationsRequest.cs
+++ b/src/constructor.io/models/Recommendations/RecommendationsRequest.cs
@@ -80,6 +80,11 @@ public RecommendationsRequest(string podId)
         /// </summary>
         public PreFilterExpression PreFilterExpression { get; set; }
 
+        /// <summary>
+        /// Gets or sets format options to control result formatting.
+        /// </summary>
+        public FmtOptions FmtOptions { get; set; }
+
         /// <summary>
         /// Get request parameters.
         /// </summary>
@@ -158,6 +163,14 @@ public Hashtable GetRequestParameters()
                 parameters.Add(Constants.PRE_FILTER_EXPRESSION, preFilterJson);
             }
 
+            if (this.FmtOptions != null)
+            {
+                foreach (DictionaryEntry entry in this.FmtOptions.GetQueryParameters())
+                {
+                    parameters.Add(entry.Key, entry.Value);
+                }
+            }
+
             return parameters;
         }