diff --git a/src/interface/iface.rs b/src/interface/iface.rs
index 8d70e5c3..fc31181a 100644
--- a/src/interface/iface.rs
+++ b/src/interface/iface.rs
@@ -37,8 +37,8 @@ use strict_encoding::{
 };
 use strict_types::{SemId, SymbolicSys, TypeLib};
 
-use crate::interface::{IfaceDisplay, IfaceImpl, VerNo};
-use crate::persistence::SchemaIfaces;
+use crate::interface::{ContractIface, IfaceDisplay, IfaceImpl, VerNo};
+use crate::persistence::{ContractStateRead, SchemaIfaces};
 use crate::LIB_NAME_RGB_STD;
 
 /// Interface identifier.
@@ -336,24 +336,25 @@ pub struct TransitionIface {
 ///
 /// Interface standards like RGB20, RGB21 and RGB25 are actually interface
 /// classes.
-///
-/// The instances implementing this trait are used as wrappers around
-/// [`ContractIface`] object, allowing a simple API matching the interface class
-/// requirements.
-pub trait IfaceClass {
+pub trait IfaceClass: Clone + Default {
     const IFACE_NAME: &'static str;
     const IFACE_IDS: &'static [IfaceId];
 
-    /// An object which allows to configure specific interface features to
-    /// select one interface from the class.
-    type Features: Sized + Clone + Default;
+    type Wrapper<S: ContractStateRead>: IfaceWrapper<S>;
 
+    fn stl(&self) -> TypeLib;
+    fn iface(&self) -> Iface;
+    fn iface_id(&self) -> IfaceId;
+}
+
+/// The instances implementing this trait are used as wrappers around
+/// [`ContractIface`] object, allowing a simple API matching the interface class
+/// requirements.
+pub trait IfaceWrapper<S: ContractStateRead> {
     /// Object which represent concise summary about a contract;
     type Info: Clone + Eq + Debug;
 
-    fn iface(features: Self::Features) -> Iface;
-    fn iface_id(features: Self::Features) -> IfaceId;
-    fn stl() -> TypeLib;
+    fn with(iface: ContractIface<S>) -> Self;
 
     /// Constructs information object describing a specific class in terms of
     /// the interface class.
diff --git a/src/interface/mod.rs b/src/interface/mod.rs
index 03a613ca..ea5ef2d9 100644
--- a/src/interface/mod.rs
+++ b/src/interface/mod.rs
@@ -41,7 +41,8 @@ pub use contractum::IfaceDisplay;
 pub use filter::{FilterExclude, FilterIncludeAll, OutpointFilter};
 pub use iface::{
     ArgMap, AssignIface, ExtensionIface, GenesisIface, GlobalIface, Iface, IfaceClass, IfaceId,
-    IfaceInconsistency, IfaceRef, Modifier, OpName, OwnedIface, Req, TransitionIface, ValencyIface,
+    IfaceInconsistency, IfaceRef, IfaceWrapper, Modifier, OpName, OwnedIface, Req, TransitionIface,
+    ValencyIface,
 };
 pub use iimpl::{IfaceImpl, ImplId, NamedField, NamedType, NamedVariant, SchemaTypeIndex};
 pub use inheritance::{CheckInheritance, ExtensionError, InheritanceFailure};
diff --git a/src/persistence/stock.rs b/src/persistence/stock.rs
index 11b282ad..6bdb663b 100644
--- a/src/persistence/stock.rs
+++ b/src/persistence/stock.rs
@@ -56,7 +56,7 @@ use crate::containers::{
 use crate::info::{ContractInfo, IfaceInfo, SchemaInfo};
 use crate::interface::{
     BuilderError, ContractBuilder, ContractIface, Iface, IfaceClass, IfaceId, IfaceRef,
-    TransitionBuilder,
+    IfaceWrapper, TransitionBuilder,
 };
 use crate::{MergeRevealError, RevealError};
 
@@ -502,12 +502,16 @@ impl<S: StashProvider, H: StateProvider, P: IndexProvider> Stock<S, H, P> {
     #[allow(clippy::multiple_bound_locations)]
     pub fn contracts_by<'a, C: IfaceClass + 'a>(
         &'a self,
-    ) -> Result<impl Iterator<Item = C::Info> + 'a, StockError<S, H, P>>
-    where C: From<ContractIface<H::ContractRead<'a>>> {
+    ) -> Result<
+        impl Iterator<
+            Item = <C::Wrapper<H::ContractRead<'_>> as IfaceWrapper<H::ContractRead<'_>>>::Info,
+        > + 'a,
+        StockError<S, H, P>,
+    > {
         Ok(self.stash.geneses_by::<C>()?.filter_map(|genesis| {
             self.contract_iface_class::<C>(genesis.contract_id())
                 .as_ref()
-                .map(C::info)
+                .map(<C::Wrapper<H::ContractRead<'_>> as IfaceWrapper<H::ContractRead<'_>>>::info)
                 .ok()
         }))
     }
@@ -547,27 +551,23 @@ impl<S: StashProvider, H: StateProvider, P: IndexProvider> Stock<S, H, P> {
     }
 
     #[allow(clippy::multiple_bound_locations)]
-    pub fn contract_iface_class<'a, C: IfaceClass>(
-        &'a self,
+    pub fn contract_iface_class<C: IfaceClass>(
+        &self,
         contract_id: ContractId,
-    ) -> Result<C, StockError<S, H, P, ContractIfaceError>>
-    where
-        C: From<ContractIface<H::ContractRead<'a>>>,
-    {
+    ) -> Result<C::Wrapper<H::ContractRead<'_>>, StockError<S, H, P, ContractIfaceError>> {
         let (schema_ifaces, state, info) = self.contract_raw(contract_id)?;
         let iimpl = self.stash.impl_for::<C>(schema_ifaces)?;
 
         let iface = self.stash.iface(iimpl.iface_id)?;
         let (types, _) = self.stash.extract(&schema_ifaces.schema, [iface])?;
 
-        Ok(ContractIface {
+        Ok(C::Wrapper::with(ContractIface {
             state,
             schema: schema_ifaces.schema.clone(),
             iface: iimpl.clone(),
             types,
             info,
-        }
-        .into())
+        }))
     }
 
     /// Returns the best matching abstract interface to a contract.