diff --git a/deno.json b/deno.json
index 2f03587..27bee31 100644
--- a/deno.json
+++ b/deno.json
@@ -1,6 +1,6 @@
 {
   "name": "@cross/kv",
-  "version": "0.0.8",
+  "version": "0.0.9",
   "exports": {
     ".": "./mod.ts"
   },
diff --git a/src/index.ts b/src/index.ts
index 2cb68bc..70c513b 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -117,17 +117,21 @@ export class KVIndex {
           recurse(childNode, keyIndex + 1);
         }
       } else if (
-        typeof keyPart === "object" &&
-        (keyPart.from !== undefined || keyPart.to !== undefined)
+        typeof keyPart === "object"
       ) {
-        // Key range
         const range = keyPart as KVKeyRange;
+
+        // Key range
         for (const [index, childNode] of node.children.entries()) {
           // Iterate over children, comparing the index to the range
           if (
+            // Shortcut for empty key = all
+            (range.from === undefined && range.to === undefined) ||
+            // String comparison
             (typeof index === "string" &&
               (range.from === undefined || index >= (range.from as string)) &&
               (range.to === undefined || index <= (range.to as string))) ||
+            // Number comparison
             (typeof index === "number" &&
               (range.from === undefined || index >= (range.from as number)) &&
               (range.to === undefined || index <= (range.to as number)))
diff --git a/src/key.test.ts b/src/key.test.ts
new file mode 100644
index 0000000..fab0e04
--- /dev/null
+++ b/src/key.test.ts
@@ -0,0 +1,75 @@
+import { assertEquals, assertThrows } from "@std/assert";
+import { test } from "@cross/test";
+import { KVKey /* ... */ } from "./key.ts";
+
+test("KVKey: constructs with valid string key", () => {
+  const key = new KVKey(["users", "user123"]);
+  assertEquals(key.get(), ["users", "user123"]);
+});
+
+test("KVKey: throws with invalid string key (colon)", () => {
+  assertThrows(
+    () => new KVKey(["users", ":lol"]),
+    TypeError,
+    "String elements in the key can only contain",
+  );
+});
+
+test("KVKey: throws with invalid string key (space)", () => {
+  assertThrows(
+    () => new KVKey(["users", "l ol"]),
+    TypeError,
+    "String elements in the key can only contain",
+  );
+});
+
+test("KVKey: constructs with valid number key", () => {
+  const key = new KVKey(["data", 42]);
+  assertEquals(key.get(), ["data", 42]);
+});
+
+test("KVKey: returns correct string representation", () => {
+  const key = new KVKey(["users", "data", "user123"]);
+  assertEquals(key.getKeyRepresentation(), "users.data.user123");
+});
+
+test("KVKey: constructs with valid range", async () => {
+  const key = new KVKey(["users", { from: "user001", to: "user999" }], true);
+  assertEquals(key.get(), ["users", { from: "user001", to: "user999" }]);
+});
+
+test("KVKey: constructs with valid range (only from)", () => {
+  const key = new KVKey(["users", { from: "user001" }], true);
+  assertEquals(key.get(), ["users", { from: "user001" }]);
+});
+
+test("KVKey: constructs with valid range (only to)", () => {
+  const key = new KVKey(["users", { to: "user001" }], true);
+  assertEquals(key.get(), ["users", { to: "user001" }]);
+});
+
+test("KVKey: constructs with valid range (all)", () => {
+  const key = new KVKey(["users", {}], true);
+  assertEquals(key.get(), ["users", {}]);
+});
+
+test("KVKey: constructs with invalid range (extra property)", () => {
+  assertThrows(
+    // @ts-expect-error test unknown property
+    () => new KVKey(["users", { test: 1 }], true),
+    TypeError,
+    "Ranges must have only",
+  );
+});
+
+test("KVKey: throws on empty key", () => {
+  assertThrows(() => new KVKey([]), TypeError, "Key cannot be empty");
+});
+
+test("KVKey: only allows string keys as first entry", () => {
+  assertThrows(
+    () => new KVKey([123121]),
+    TypeError,
+    "First index of the key must be a string",
+  );
+});
diff --git a/src/key.ts b/src/key.ts
index 309e8f5..92a0246 100644
--- a/src/key.ts
+++ b/src/key.ts
@@ -1,4 +1,4 @@
-export const KV_KEY_ALLOWED_CHARS = /^[a-zA-Z0-9\-_]+$/;
+export const KV_KEY_ALLOWED_CHARS = /^[a-zA-Z0-9\-_@]+$/;
 
 export interface KVKeyRange {
   from?: string | number;
@@ -39,9 +39,18 @@ export class KVKey {
       }
 
       if (typeof element === "object") {
-        if (!(element.from || element.to)) {
+        const allowedKeys = ["from", "to"];
+        const elementKeys = Object.keys(element);
+
+        // Check for empty object
+        if (elementKeys.length === 0) {
+          return; // Allow an empty object
+        }
+
+        // Check for additional keys
+        if (!elementKeys.every((key) => allowedKeys.includes(key))) {
           throw new TypeError(
-            'Ranges must have one or both of "from" and "to"',
+            'Ranges must have only "from" and/or "to" keys',
           );
         }
       }
diff --git a/src/kv.test.ts b/src/kv.test.ts
index e3b607e..518f656 100644
--- a/src/kv.test.ts
+++ b/src/kv.test.ts
@@ -143,6 +143,51 @@ test("KV: supports numeric key ranges", async () => {
   assertEquals(rangeResults[2].data, "Value 9");
 });
 
+test("KV: supports additional levels after numeric key ranges", async () => {
+  const tempFilePrefix = await tempfile();
+  const kvStore = new KV();
+  await kvStore.open(tempFilePrefix);
+
+  // Set some values within a range
+  for (let i = 5; i <= 10; i++) {
+    await kvStore.set(["data", i, "doc1"], `Value ${i} in doc1`);
+    await kvStore.set(["data", i, "doc2"], `Value ${i} in doc2`);
+  }
+
+  // Test if the 'get' function returns the expected values
+  const rangeResults = await kvStore.getMany([
+    "data",
+    { from: 7, to: 9 },
+    "doc1",
+  ]);
+  assertEquals(rangeResults.length, 3);
+  assertEquals(rangeResults[0].data, "Value 7 in doc1");
+  assertEquals(rangeResults[1].data, "Value 8 in doc1");
+  assertEquals(rangeResults[2].data, "Value 9 in doc1");
+});
+
+test("KV: supports empty numeric key ranges to get all", async () => {
+  const tempFilePrefix = await tempfile();
+  const kvStore = new KV();
+  await kvStore.open(tempFilePrefix);
+
+  // Set some values within a range
+  for (let i = 5; i <= 10; i++) {
+    await kvStore.set(["data", i, "doc1"], `Value ${i} in doc1`);
+    await kvStore.set(["data", i, "doc2"], `Value ${i} in doc2`);
+  }
+
+  // Test if the 'get' function returns the expected values
+  const rangeResults = await kvStore.getMany(["data", {}, "doc1"]);
+  assertEquals(rangeResults.length, 6);
+  const rangeResults2 = await kvStore.getMany(["data", {}, "doc2"]);
+  assertEquals(rangeResults2.length, 6);
+  const rangeResults3 = await kvStore.getMany(["data", {}]);
+  assertEquals(rangeResults3.length, 12);
+  const rangeResults4 = await kvStore.getMany(["data"]);
+  assertEquals(rangeResults4.length, 12);
+});
+
 test("KV: supports string key ranges", async () => {
   const tempFilePrefix = await tempfile();
   const kvStore = new KV();