Check the listing for details. MP5 Mag Block - Empty Chamber Indicators (ECI) - keychain Yippee Ki-Yay. Condition: New. Listed at 12.99 USD. This device fits into the magazine well to indicate that the weapon is unloaded and safe. A requirement at a gun range. The top of the mag block will appear in the extraction port with the word SAFE visible. The bolt will be blocked from closing. The mag block will lock in when inserted and will require the mag release to be pressed to remove it. This mag block fits the HK MP5, MP5k, SP5, SP5K and the various clones only. The size is similar to the length of a 10 rounder. A keychain is included with the mag block. The Yippee Ki-Yay flag is a special design I made specifically for this mag block. This is 3d printed using durable PLA plus filament. Estimated Dimensions:42.5 mm x 27 mm x 129 mm1.7 in. x 1 in. x 5.1 in. Thank you for viewing the product.