Great magazine. Holds over 400 rounds for continuous firing. The attachments on the side of the mag are strong, sturdy and attach easily. The winding wheel on the bottom of the mag is easy to wind with or without gloves, and the wheel is easy to locate without looking.
The overall construction of the magazine is exceptional. The mag is constructed out of a strong plastic. The filling door on the top of the magazine is big enough to fill using a speedloader nozzel on a bottle of bb's, and it locks in place securely, with no chance of it opening accidentally.
In summary 10 out of 10, 5 stars. I would definitely buy again and recommend to friends.
Major Thumbs Up to Zeroone.