Lee Enfield magazine

Selling a Lee Enfield magazine. I'm not very confident which model it's for. Been told it's a  series 4 for No.1 mk.3 SMLE. Found in grandpas collection and doesn't fit/work in his Lee Enfield so not sure where it came from. 

Will trade for ammo. 

If you need more pictures to identify it lmk.

Thanks