I have a custom meta box with two different radio buttons that can be selected.
One is for displaying the content in a "large' format, the other is for displaying content in a "small" format on the front end. 

I already know how to retrieve a meta box's data and output it, but not how to "check" what specific data has been selected, and how to that output according to what value has been selected. (**It should be noted that I will be using this data to output a specific CSS class that can then be applied to a different block of code designated for that selection**)

Here is what i have for my meta box (UPDATED):<br/>

    <?php
    // Register Custom Post Type Meta Box for EPR Music Releases CPT -- Album Sizes
    add_action( 'add_meta_boxes', 'musicreleases_albumsize_meta_box_add' );
    function musicreleases_albumsize_meta_box_add()
    {
    	add_meta_box( 'musicreleases_albumsize_meta_id', 'Album Size', 'musicreleases_albumsize_meta_box_cb', 'eprmusicrelease', 'normal', 'low' );
    }
    
    function musicreleases_albumsize_meta_box_cb( $post )
    {
        $value = get_post_meta( $post->ID,'meta_box_musicreleases_albumsize',true );
        wp_nonce_field( 'my_meta_box_nonce', 'meta_box_nonce' );
        ?>
        <p>
            <input type="radio" name="albumsize" value="album_small" <?php echo ($value == 'album_small')? 'checked="checked"':''; ?>/> Small<br />
            <input type="radio" name="albumsize" value="album_large" <?php echo ($value == 'album_large')? 'checked="checked"':''; ?>/> Large<br />
        </p>
        <?php   
    }
    
    add_action( 'save_post', 'musicreleases_albumsize_meta_box_save' );
    function musicreleases_albumsize_meta_box_save( $post_id ){
        if( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) return;
        if( !isset( $_POST['meta_box_nonce'] ) || !wp_verify_nonce( $_POST['meta_box_nonce'], 'my_meta_box_nonce' ) ) return;
        if( !current_user_can( 'edit_post' ) ) return;
    
        //accepted values whitelist
        $allowed = array('album_small','album_large');
    
        if( isset( $_POST['albumsize'] )  && in_array($_POST['albumsize'], $allowed))
            update_post_meta( $post_id, 'meta_box_musicreleases_albumsize',  $_POST['albumsize'] );
    }
    ?>

...As you can see, the meta box allows the user to select whether the album is to be displayed as a LARGE or SMALL release.

**This is my current template which I need to add this data to for the front end (UPDATED):**

    <?php
    /*
    Template Name: Music Releases
    */
    ?>
    	
    <div class="widget_wrapper">
    
    	<h2 class="widgettitle">Releases</h2>
    
    	<?php $music_releases = new WP_Query(array('post_type' => 'eprmusicrelease')); ?>
    	<?php if($music_releases->have_posts()): while ($music_releases->have_posts() ) : $music_releases->the_post(); ?>
    		
    		<?php if($album_url = get_post_meta($post->ID, 'meta_box_musicreleases_url', true)): ?>
    			
    			<?php $album_size = get_post_meta( $post->ID,'meta_box_musicreleases_albumsize',true ); ?>
    			<?php if($album_size == 'album_small'): ?>
    							
    					<div class="release_small">
    						<a href="<?php echo esc_url($album_url); ?>" title="<?php the_title_attribute(); ?>" target="_blank"></a>
    						<?php if($url_type = get_post_meta($post->ID, 'meta_box_musicreleases_linktype', true)): ?>
    							<div class="<?php echo ($url_type); ?>"></div>
    						<?php else: ?>
    						<?php endif; ?>
    						<?php the_post_thumbnail('music-release-img-sm'); ?>
    					</div>
    					
    			<?php elseif($album_size == 'album_large'): ?>
    							
    				<div class="release_large">
    					<a href="<?php echo esc_url($album_url); ?>" title="<?php the_title_attribute(); ?>" target="_blank"></a>
    					<?php if($url_type = get_post_meta($post->ID, 'meta_box_musicreleases_linktype', true)): ?>
    						<div class="<?php echo ($url_type); ?>"></div>
    					<?php else: ?>
    					<?php endif; ?>
    					<?php the_post_thumbnail('music-release-img-lrg'); ?>
    				</div>
    			
    			<?php else: ?>
    			
    				<!-- no radio button selected -->
    				<div class="release_large">
    					<a href="<?php echo esc_url($album_url); ?>" title="<?php the_title_attribute(); ?>" target="_blank"></a>
    					<?php if($url_type = get_post_meta($post->ID, 'meta_box_musicreleases_linktype', true)): ?>
    						<div class="<?php echo ($url_type); ?>"></div>
    					<?php else: ?>
    					<?php endif; ?>
    					<?php the_post_thumbnail('music-release-img-lrg'); ?>
    				</div>
    					
    			<?php endif; ?>
    			
    		<?php else: ?>
    		
    			<?php $album_size = get_post_meta( $post->ID,'meta_box_musicreleases_albumsize',true ); ?>
    			<?php if($album_size == 'album_small'): ?>
    							
    					<div class="release_small">
    						<?php if($url_type = get_post_meta($post->ID, 'meta_box_musicreleases_linktype', true)): ?>
    							<div class="<?php echo ($url_type); ?>"></div>
    						<?php else: ?>
    						<?php endif; ?>
    						<?php the_post_thumbnail('music-release-img-sm'); ?>
    					</div>
    					
    			<?php elseif($album_size == 'album_large'): ?>
    							
    				<div class="release_large">
    					<?php if($url_type = get_post_meta($post->ID, 'meta_box_musicreleases_linktype', true)): ?>
    						<div class="<?php echo ($url_type); ?>"></div>
    					<?php else: ?>
    					<?php endif; ?>
    					<?php the_post_thumbnail('music-release-img-lrg'); ?>
    				</div>
    			
    			<?php else: ?>
    			
    				<!-- no radio button selected -->
    				<div class="release_large">
    					<?php if($url_type = get_post_meta($post->ID, 'meta_box_musicreleases_linktype', true)): ?>
    						<div class="<?php echo ($url_type); ?>"></div>
    					<?php else: ?>
    					<?php endif; ?>
    					<?php the_post_thumbnail('music-release-img-lrg'); ?>
    				</div>
    					
    			<?php endif; ?>
    		
    		<?php endif; ?>
    	
    	<?php endwhile; else: // NO POSTS // ?>	
    	<?php endif; ?>
    	<?php wp_reset_query(); ?>
    	
    </div>