diff --git a/src/utils/device.jl b/src/utils/device.jl
index 627095b..ca3f6c1 100644
--- a/src/utils/device.jl
+++ b/src/utils/device.jl
@@ -13,28 +13,29 @@ send_to_device(::Val{:cpu}, x) = x  # cpu(x) is not very efficient! So by defaul
 
 send_to_device(::Val{:cpu}, x::CuArray) = adapt(Array, x)
 send_to_device(::Val{:gpu}, x) = Flux.fmap(a -> adapt(CuArray{Float32}, a), x)
-send_to_device(
-    ::Val{:gpu},
-    x::Union{
-        SubArray{<:Any,<:Any,<:Union{CircularArrayBuffer,ElasticArray}},
-        Base.ReshapedArray{
-            <:Any,
-            <:Any,
-            <:SubArray{<:Any,<:Any,<:Union{CircularArrayBuffer,ElasticArray}},
-        },
-        Base.ReshapedArray{<:Any,<:Any,<:Union{CircularArrayBuffer,ElasticArray}},
-        SubArray{
+
+const KnownArrayVariants = Union{
+    SubArray{<:Any,<:Any,<:Union{ReservoirArrayBuffer,CircularArrayBuffer,ElasticArray}},
+    Base.ReshapedArray{
+        <:Any,
+        <:Any,
+        <:SubArray{<:Any,<:Any,<:Union{ReservoirArrayBuffer,CircularArrayBuffer,ElasticArray}},
+    },
+    Base.ReshapedArray{<:Any,<:Any,<:Union{ReservoirArrayBuffer,CircularArrayBuffer,ElasticArray}},
+    SubArray{
+        <:Any,
+        <:Any,
+        <:Base.ReshapedArray{
             <:Any,
             <:Any,
-            <:Base.ReshapedArray{
-                <:Any,
-                <:Any,
-                <:SubArray{<:Any,<:Any,<:Union{CircularArrayBuffer,ElasticArray}},
-            },
+            <:SubArray{<:Any,<:Any,<:Union{ReservoirArrayBuffer,CircularArrayBuffer,ElasticArray}},
         },
-        ElasticArray,
     },
-) = CuArray(x)
+}
+
+# https://github.com/JuliaReinforcementLearning/ReinforcementLearningCore.jl/issues/130
+send_to_device(::Val{:cpu}, x::KnownArrayVariants) = Array(x)
+send_to_device(::Val{:gpu}, x::Union{KnownArrayVariants, ElasticArray}) = CuArray(x)
 
 """
     device(model)
diff --git a/src/utils/reservoir_array_buffer.jl b/src/utils/reservoir_array_buffer.jl
new file mode 100644
index 0000000..717ee51
--- /dev/null
+++ b/src/utils/reservoir_array_buffer.jl
@@ -0,0 +1,31 @@
+export ReservoirArrayBuffer
+
+using Random
+using ElasticArrays
+using MacroTools:@forward
+
+mutable struct ReservoirArrayBuffer{T, N, B<:ElasticArray{T, N}, R<:AbstractRNG} <: AbstractArray{T, N}
+    buffer::B
+    n::Int
+    capacity::Int
+    rng::R
+end
+
+ReservoirArrayBuffer{T}(dims::Int...;rng=Random.GLOBAL_RNG) where {T} = ReservoirArrayBuffer(ElasticArray{T}(undef, dims[1:end-1]..., 0), 0, dims[end], rng)
+
+@forward ReservoirArrayBuffer.buffer Base.size, Base.getindex, Base.length, Base.sizeof, Base.IndexStyle
+
+# TODO: rename all push! to append!
+
+function Base.push!(b::ReservoirArrayBuffer{T, N}, x) where {T, N}
+    b.n += 1
+    if b.n <= b.capacity
+        append!(b.buffer, x)
+    else
+        i = rand(b.rng, 1:b.n)
+        if i <= b.capacity
+            stride = b.buffer.kernel_length.divisor
+            b.buffer.data[(stride*(i-1)+1): stride*i] .= x
+        end
+    end
+end
diff --git a/src/utils/utils.jl b/src/utils/utils.jl
index be1556d..9ba0032 100644
--- a/src/utils/utils.jl
+++ b/src/utils/utils.jl
@@ -1,5 +1,6 @@
 include("printing.jl")
 include("base.jl")
 include("circular_array_buffer.jl")
+include("reservoir_array_buffer.jl")
 include("device.jl")
 include("sum_tree.jl")
diff --git a/test/utils/reservoir_array_buffer.jl b/test/utils/reservoir_array_buffer.jl
new file mode 100644
index 0000000..c6958fe
--- /dev/null
+++ b/test/utils/reservoir_array_buffer.jl
@@ -0,0 +1,16 @@
+@testset "ReservoirArrayBuffer" begin
+    b = ReservoirArrayBuffer{Int}(3, 2)
+    @assert size(b) == (3, 0)
+
+    push!(b, [1,1,1])
+    @assert size(b) == (3, 1)
+    @test all(b .== [1;1;1])
+
+    push!(b, [2,2,2])
+    @assert size(b) == (3, 2)
+    @test all(b .== [1 2;1 2;1 2])
+
+    push!(b, [0,0,0])
+
+    @test size(b) == (3, 2)
+end
\ No newline at end of file
diff --git a/test/utils/utils.jl b/test/utils/utils.jl
index 7a7715c..bca9bdb 100644
--- a/test/utils/utils.jl
+++ b/test/utils/utils.jl
@@ -1,3 +1,4 @@
 include("base.jl")
 include("circular_array_buffer.jl")
+include("reservoir_array_buffer.jl")
 include("device.jl")