diff --git a/src/niquests/__init__.py b/src/niquests/__init__.py
index 4ebf0d58eb..e3345b7150 100644
--- a/src/niquests/__init__.py
+++ b/src/niquests/__init__.py
@@ -57,10 +57,9 @@ def check_compatibility(urllib3_version, charset_normalizer_version) -> None:
     # Check urllib3 for compatibility.
     major, minor, patch = urllib3_version  # noqa: F811
     major, minor, patch = int(major), int(minor), int(patch)
-    # urllib3 >= 1.21.1
-    assert major >= 1
-    if major == 1:
-        assert minor >= 21
+    # urllib3 >= 2.0.9xx
+    assert major >= 2
+    assert patch >= 900
 
     # Check charset_normalizer for compatibility.
     major, minor, patch = charset_normalizer_version.split(".")[:3]
diff --git a/src/niquests/_constant.py b/src/niquests/_constant.py
index dee6761aec..c558412d71 100644
--- a/src/niquests/_constant.py
+++ b/src/niquests/_constant.py
@@ -4,3 +4,7 @@
 READ_DEFAULT_TIMEOUT: TimeoutType = 30
 #: Default timeout (total) assigned for DELETE, PUT, PATCH, and POST.
 WRITE_DEFAULT_TIMEOUT: TimeoutType = 120
+
+DEFAULT_POOLBLOCK: bool = False
+DEFAULT_POOLSIZE: int = 10
+DEFAULT_RETRIES: int = 0
diff --git a/src/niquests/adapters.py b/src/niquests/adapters.py
index 328f7b6d84..e622a6e924 100644
--- a/src/niquests/adapters.py
+++ b/src/niquests/adapters.py
@@ -31,6 +31,7 @@
 from urllib3.util import parse_url
 from urllib3.util.retry import Retry
 
+from ._constant import DEFAULT_POOLBLOCK, DEFAULT_POOLSIZE, DEFAULT_RETRIES
 from ._typing import CacheLayerAltSvcType, ProxyType, TLSClientCertType, TLSVerifyType
 from .auth import _basic_auth_str
 from .cookies import extract_cookies_to_jar
@@ -66,12 +67,6 @@ def SOCKSProxyManager(*args: typing.Any, **kwargs: typing.Any) -> None:  # type:
         raise InvalidSchema("Missing dependencies for SOCKS support.")
 
 
-DEFAULT_POOLBLOCK = False
-DEFAULT_POOLSIZE = 10
-DEFAULT_RETRIES = 0
-DEFAULT_POOL_TIMEOUT = None
-
-
 class BaseAdapter:
     """The Base Transport Adapter"""
 
@@ -129,9 +124,9 @@ class HTTPAdapter(BaseAdapter):
 
     Usage::
 
-      >>> import requests
-      >>> s = requests.Session()
-      >>> a = requests.adapters.HTTPAdapter(max_retries=3)
+      >>> import niquests
+      >>> s = niquests.Session()
+      >>> a = niquests.adapters.HTTPAdapter(max_retries=3)
       >>> s.mount('http://', a)
     """
 
diff --git a/src/niquests/api.py b/src/niquests/api.py
index 74153685ec..c2f428fa42 100644
--- a/src/niquests/api.py
+++ b/src/niquests/api.py
@@ -86,8 +86,8 @@ def request(
 
     Usage::
 
-      >>> import requests
-      >>> req = requests.request('GET', 'https://httpbin.org/get')
+      >>> import niquests
+      >>> req = niquests.request('GET', 'https://httpbin.org/get')
       >>> req
       <Response HTTP/2 [200]>
     """
diff --git a/src/niquests/models.py b/src/niquests/models.py
index f98debb511..a564c86b7c 100644
--- a/src/niquests/models.py
+++ b/src/niquests/models.py
@@ -124,8 +124,8 @@ class Request:
 
     Usage::
 
-      >>> import requests
-      >>> req = requests.Request('GET', 'https://httpbin.org/get')
+      >>> import niquests
+      >>> req = niquests.Request('GET', 'https://httpbin.org/get')
       >>> req.prepare()
       <PreparedRequest [GET]>
     """
@@ -219,13 +219,13 @@ class PreparedRequest:
 
     Usage::
 
-      >>> import requests
-      >>> req = requests.Request('GET', 'https://httpbin.org/get')
+      >>> import niquests
+      >>> req = niquests.Request('GET', 'https://httpbin.org/get')
       >>> r = req.prepare()
       >>> r
       <PreparedRequest [GET]>
 
-      >>> s = requests.Session()
+      >>> s = niquests.Session()
       >>> s.send(r)
       <Response HTTP/2 [200]>
     """
diff --git a/src/niquests/sessions.py b/src/niquests/sessions.py
index 0607b0d5b1..015354bc18 100644
--- a/src/niquests/sessions.py
+++ b/src/niquests/sessions.py
@@ -136,14 +136,14 @@ class Session:
 
     Basic Usage::
 
-      >>> import requests
-      >>> s = requests.Session()
+      >>> import niquests
+      >>> s = niquests.Session()
       >>> s.get('https://httpbin.org/get')
       <Response HTTP/2 [200]>
 
     Or as a context manager::
 
-      >>> with requests.Session() as s:
+      >>> with niquests.Session() as s:
       ...     s.get('https://httpbin.org/get')
       <Response HTTP/2 [200]>
     """
diff --git a/src/niquests/status_codes.py b/src/niquests/status_codes.py
index 4bd072be97..d16ed9f5f6 100644
--- a/src/niquests/status_codes.py
+++ b/src/niquests/status_codes.py
@@ -5,12 +5,12 @@
 
 Example::
 
-    >>> import requests
-    >>> requests.codes['temporary_redirect']
+    >>> import niquests
+    >>> niquests.codes['temporary_redirect']
     307
-    >>> requests.codes.teapot
+    >>> niquests.codes.teapot
     418
-    >>> requests.codes['\o/']
+    >>> niquests.codes['\o/']
     200
 
 Some codes have multiple names, and both upper- and lower-case versions of