introduced by Tokyo Marui in 2005 with their Glock 18C (followed later by a Beretta 93R model). They were the first handguns to incorporate an electrically powered system that is capable of fully automatic operation. In cold weather, AEPs are often considered better sidearms than gas powered pistols, because batteries are not as badly affected by frigid weather. Gases like CO2 and green gas are stored in liquid form and require heat in order to vaporize. A gas pistol at will usually only get one to two usable shots from a full magazine, and even will be at reduced power because of the lowered pressure of the gas. Because the AEP gearbox and battery are smaller, the velocity of AEP BBs (usually between 200 and ) is relatively slow by the standards of airsoft simulations, rendering them useful only for close-range simulation. However, the advanced hop up units on these new guns tend to compensate for the low power and can produce an effective range comparable to those of an AEG. CYMA has made a clone Glock 18C, which is a lower priced alternative. An AEP differs from electric blow-backs because the AEP has a fixed slide (in which there is no external movement of the slide during operation), while an EBB simulates the "blow back" action in the slide experienced in a real pistol or Gas Blow Back (GBB). An AEP, however, has much more power and accuracy. One of the newer AEP-styled guns is the Marui replica of the Heckler & Koch MP7. It is considerably larger than either of the other guns, and can be upgraded to a much higher power through the use of an external battery, but uses the same system as the AEP, so the classification is ambiguous. It is slightly more powerful than the others and is a suitable choice for CQB (Close Quarter Battle) games due to its small size and decent barrel- to gun-length ratio. Some semi-automatic pistols can be modified to be automatic pistols. To make them more effective, they use rechargeable batteries supplied with the gun, and can be replaced with a larger battery to make their ROF higher. Due to restrictions on size, either the electric motor or batteries have to occupy space in the hand grip, reducing the available space for a magazine. Because of this, most AEPs do not use a full size magazine found in