The key to listening centers is the jackbox, the distribution point to the headphones. Califone gives more attention to this eight-position jackbox with features such as silver-plated contact points for a solid connection and moisture resistance, individual volume controls, and rugged ABS plastic housing for durability. Ideal for use in Listening Centers, ELD/ELL and Special Education applications, Language Labs and literacy groups.• Eight learning positions, each with a 1/4" jack and individual volume control• Rugged ABS plastic casing for durability and school safety• Permanently attached 6' cord with 1/4" and 3.5mm plugs connects with media players• Silver-plated contacts prevent " crackling" sound heard with other jackboxes when connecting• Skid-resistant pads at each corner won't mar or scrape surface• Two predrilled holes to permanently affix to a surface